Colombo Xamarin Meetup – June 2017 -[Session 2] – Xamarin Forms Rich UI Controls – By : Buddhima Kudagama

Session 2 : Xamarin Forms Rich UI Controls

Hi Guys, This is our 8th Meetup of Colombo Xamarin Meetup group. I’m happy to say you that we have successfully done our meetup on 29th June 2017 in CMS , Colombo with two sessions.

I have done the 2nd session about Xamarin Forms Rich User interface controls with a demo and this article is about my session.

https://www.meetup.com/Colombo-Xamarin-Meetup/events/241017250/

 

Slide1.PNG

Image 1 : Colombo Xamarin Meetup

Click below link to Download the Slide of Session 2 –

[Xamarin forms Rich UI Controls] : Meetup20170629.Buddhima.ppt

You can have the sample App here…

https://drive.google.com/open?id=0B2gY_8MAQPWnQnZERi03Y0hENk0

What are the the rich UI controls available for Xamarin forms ?

I found some third party controls which are available for xamarin forms and xamarin native development and here are some main providers and their controls…

Slide3.PNG

Image 2 : Rich UI control providers

Syncfusion – https://www.syncfusion.com/products/xamarin

Infragistics – https://www.infragistics.com/products/xamarin

Telerik – http://www.telerik.com/xamarin-ui

DevExpress – https://www.devexpress.com/products/xamarin/

First of All you should have a idea about Layouts, Pages, Views and Controls in Xamain Forms Mobile applications..

So Please Use these reference to learn them…

https://developer.xamarin.com/guides/xamarin-forms/user-interface/controls/pages/

https://developer.xamarin.com/guides/xamarin-forms/user-interface/controls/layouts/

How to Design the User Interface(UI) in Xamarin Forms ?

There are two main methods :

  1. Design using XAML (Extensible Application Markup Language)
  2. using C# code in code behind

but you can design the UI using both of them…

What’s going to do ?

Syncfusion is better to develop Xamarin apps because of …

syncfusion.png

  • It gives a community license
  • and It has large number of controls than other third-party control providers.
  • Its very flexible to use
  • Good customer support etc.

How to Get the Free Community License ?

To get the community licence, go to..

https://www.syncfusion.com/products/xamarin

https://www.syncfusion.com/products/communitylicense

When you claim the license by registering with syncfusion , they will send you the licence code for the product and you have to use it in the installation of the package…

How to Get the Syncfusion Packages to the Application ?

There are two methods to get the packages..

  1. Get using NuGet
  2. Direct Download using web site

You can follow the user guide to see how to download and Install the package in both of above methods..

Click here to see the user guide for download and installation …

https://help.syncfusion.com/xamarin/introduction/download-and-installation

How to Download Syncfusion Xamarin from Nu Get ?

In Visual Studio go to …

  1. Tools -> Options -> NuGet Package Manager -> Package Sources. By default You can see default NuGet packages are there.
0. default packages.jpg

Image 3 : Add new packages to NuGet Gallery

  1. To Add Syncfusion packages, Click Add Button in the top Right side..
  2. Then Copy and paste below URL in the bottom of the window like following image..

http://nuget.syncfusion.com/nuget_xamarin/nuget/getsyncfusionpackages/xamarin

When you add the name and source, Click “Update” and then Click “OK

1. add nuget.jpg

Image 4 : Add Syncfusion Packages to NuGet Gallery

Now you can search the Syncfusion controls in the NuGet Package manager in Visual Studio..

Now right Click on the Solution -> Manage NuGet Packages for Solution -> you will see the Package Manager dialogue like below and you will see the Syncfusion packages has been added in package sources drop down list..

2 sf in pkg mgr.jpg

Image 5 : Select Syncfusion Packages

Click on Syncfusion Packages and then the syncfusion packages will be loaded to the list.

3 packages will be loaded.jpg

Image 6 : Search NuGet packages

Syncfusion Controls for Xamarin

There are many useful controls for Xamarin has been provided by Syncfusion and I have added them to my power point Slide and please see to to get them..

You can see them here in their website..

https://www.syncfusion.com/products/xamarin/chart

and their user guide..

https://help.syncfusion.com/xamarin/sfbusyindicator/animationtype

How to Manage References/Dependencies of Controls in a Xamarin Forms App ?

Here I have taken he dependencies for Syncfusion chart to explain how the dependencies need to be added to the solution.

4 references.jpg

Image 7 : Dependencies

I have highlighted Syncfusion.SfChart.XForms.dll in Green color here and It has been added to all projects in the solution. The reason is the dll contains the common xamarin forms features and behaviors of Chart controls for all projects. So it should be added to all.

And in Yellow color, I have highlighted the platform specific dll(class library) files that we have to be added to native projects.

The best practice is follow the Syncfusion user guide when adding dependencies to any of their controls.

You can have the List of dependencies here…

https://help.syncfusion.com/xamarin/introduction/control-dependencies

You have to take care of dependencies when you are adding the references manually to your projects.

But when you are adding any controls from NuGet, it automatically installed the necessary dependencies itself.

Lets Develop a Demo App

In the session I did show you how to add Syncfusion Auto Complete Control and how to customize it.

Now lets do from the scratch.. !

Lets add dependencies to the project..

I’m using Visual Studio 2017 for the demo and OS is Windows 10.

Open Visual Studio and Go to File -> New -> New Project

Select Cross-platform in the right side of the window and select Cross Platform app (Xamarin) in Left side which shows project templates..

Then Give a Name to the app. I’ll give “DemoApp” as the Name. and Click “OK”

6 Create project.jpg

Image 8 : Select Project type to create

Now you will see another window to Select the Project Template, UI technology and code sharing strategy.

I’ll select Blank app as Template, Xamarin forms as UI technology and PCL(Portable class library) as code sharing technology for my demo.

7 select type of ui.jpg

Image 9 : Select Template

Now the project will be created and you will see it like below… The project consists of PCL, Android, iOS and a UWP project.

8 default project.jpg

Image 10 : Created Solution with projects

Then I’ll add here three folders to separate Models, View Models and Views and then the project will be like below.

5 create project.jpg

Image 11 : Model, View and ViewModel folders Create

Now Lets Install the dependencies for Syncfusion Auto Complete Control (SfAutoComplete).

SfAutoComplete is a control just like a Combo box that we use in Windows and web application.

Syncfusion Auto Complete for Xamarin.Forms provides a simpler way to complete the text based on the letters that the we entered on the box. It also provides option to choose a suggestion from drop down or append a suggestion to the text directly.

For more info, Go to …

https://help.syncfusion.com/xamarin/sfautocomplete/overview

Install using NuGet

Right Click on the Solution and -> Manage NuGet Packages

Then Select the SfAutoComplete control, Add it to all project by check the check boxes in the right side of the window.

And then Click install… And follow below steps to add the package…

9 instal control.jpg

Image 12 : Add SfAutoComplete from NuGet

10 instal control.jpg

Image 13 : Conform install the package

11 instal control.jpg

Image 14 : Accept licence

Now you can see the SfAutoComplete libraries has been added to the projects inside the solution..

I’m going to create a Android application and so I’ll show here how the references has been added to PCL and Android projects..

12 added to pcl.jpg

Image 15 : SfAutoComplete reference has been added to PCL

13 added to android.jpg

Image 16 : SfAutoComplete references has been added to Android

Now, Lets Start Coding…

Create Model

First I’ll create a Model inside of the Model Folder which “Student”..

namespace DemoApp.Model
{
public class Student
{
private int id;
public int ID
{
get { return id; }
set { id = value; }
}
private string name;
public string Name
{
get { return name; }
set { name = value; }
}

private string image;
public string Image
{
get { return image; }
set { image = value; }
}
}
}

Create View Model

And will Create A ViewModel inside the ViewModel folder as “StudentViewModel”. and I have created a Collection of Stundets in it as “StudentCollection”.


namespace DemoApp.ViewModel
{
public class StudentViewModel
{
private List<Student> studentCollection;
public List<Student> StudentCollection
{
get { return studentCollection; }
set { studentCollection = value; }
}

public StudentViewModel()
{
studentCollection = new List<Student>();
studentCollection.Add(new Student() { ID = 1, Name = "Buddhima", Image = "Student.png"});
studentCollection.Add(new Student() { ID = 2, Name = "Buddhika", Image = "Student.png"});
studentCollection.Add(new Student() { ID = 3, Name = "Dickson", Image = "Student.png" });
studentCollection.Add(new Student() { ID = 4, Name = "Janith", Image = "Student.png"});
studentCollection.Add(new Student() { ID = 5, Name = "Vidura", Image = "Student.png"});
studentCollection.Add(new Student() { ID = 6, Name = "Charitha", Image = "Student.png" });
studentCollection.Add(new Student() { ID = 7, Name = "Vimukthi", Image = "Student.png"});
studentCollection.Add(new Student() { ID = 8, Name = "Buddhi", Image = "Student.png"});
studentCollection.Add(new Student() { ID = 9, Name = "Buwaneka", Image = "Student.png"});
}
}
}

in the above code you can see there is a property called “Image” which is a image to show the student. So I have added an  Image in the Android project.

To add Images we have to go to Resources folder in Android project and there are separate folders to add images for different dimensions of devices which are drawable, drawable-hdpi, drawable-xhdpi, drawable-xxhdpi. The image has to be added to all folders according to compatible sizes with the same name.

14 Image added.jpg

Image 17 : Add Images

Design the View/User Interface

Right Click on Views folder and Click Add..

Select Xamarin forms -> and Content page as template -> Give a name -> Click OK

15 add view.jpg

Image 18 : Add a View

Then the View will be added inside of the folder with its default template with a XAML UI and a C# code behind class. (StudentView.xaml and StudentView.xaml.cs).

StudentView.xaml may be like below code…


<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="DemoApp.View.StudentView">
<ContentPage.Content>
<StackLayout>
<Label Text="Welcome to Xamarin Forms!" />
</StackLayout>
</ContentPage.Content>
</ContentPage>

StudentView.xaml.cs may be like below code…


using Xamarin.Forms;
using Xamarin.Forms.Xaml;

namespace DemoApp.View
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class StudentView : ContentPage
{
public StudentView()
{
InitializeComponent();
}
}
}

[XamlCompilation(XamlCompilationOptions.Compile)] annotation use to increase the performance of the UI in compiling which has been designed using XAML.

Now lets add the SfAutoComple to the View.

To Add any third-party Control to the XAML UI, we have to add its namespace into the Header of the Page.

So, I’ll add the namespace of SfAutoComplete  to the header of the Content Page.

xmlns:autocomplete=”clr-namespace:Syncfusion.SfAutoComplete.XForms;
assembly=Syncfusion.SfAutoComplete.XForms”

And I’ll add the control inside a Stack layout.. The design of the view should be add inside the  tag.

We can call the control by the namespace that we have added to the page header and here you can see how we can call the SfAutoComplete control.


<autocomplete:SfAutoComplete>
</autocomplete:SfAutoComplete>

And then the Code of the view like below. You can see a label also inside the Stack layout which has added when create the form.


<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:autocomplete="clr-namespace:Syncfusion.SfAutoComplete.XForms; assembly=Syncfusion.SfAutoComplete.XForms" x:Class="DemoApp.View.StudentView">
<ContentPage.Content>
<StackLayout>
<Label Text="Auto Complete control" />
<autocomplete:SfAutoComplete>
</autocomplete:SfAutoComplete>
</StackLayout>
</ContentPage.Content>
</ContentPage>

Then Lets Bind Data to the SfAutoComplete control

I’m going to bind Student Collection as data to the control using MVVM pattern. and there are two ways to Bind data using MVVM (Model View ViewModel).

  1. using XAML
  2. using C# in code behind

SfAutoComplete Control allow us to Bind a List of Strings or a List of Business Objects as the DataSource. In this Example I’m binding a List of Students to the control.

To learn more about MVVM in Xamain Please follow these links..

https://developer.xamarin.com/guides/xamarin-forms/creating-mobile-apps-xamarin-forms/summaries/chapter18/

https://developer.xamarin.com/guides/xamarin-forms/xaml/xaml-basics/data_bindings_to_mvvm/

In this example, I’ll bind data using XAML.  And will set the Binding context to the View using code behind.

Now I’mm Bind the Student View Model to the StudentView Page. We have to set the binding context inside the constructor of the view page.

[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class StudentView : ContentPage
{
public StudentView()
{
InitializeComponent();
this.BindingContext = new ViewModel.StudentViewModel();
}
}

And then need to Bind the DataSource to the SfAutoComplete Control. In XAML page, bind StudentCollection List in the StudentVoewModel to the DataSource Property as below.


<autocomplete:SfAutoComplete DataSource="{Binding StudentCollection}">
</autocomplete:SfAutoComplete>

Set the Student View Startup page …

Set the main page to StudentView in App.xaml.cs in PCL project..


public App()
{
InitializeComponent();

MainPage = new DemoApp.View.StudentView();
}

But when you run the android app, it will not show the data inside of the control.

The reason is you haven’t bind the display value to it.

Then Lest set the additional attributes..

Now we can set which value can be show inside the Control and what will be the Selected Value of the control.

DisplayMemberPath – What should me the display member

SelectedValuePath – what should be the selected value


<autocomplete:SfAutoComplete DataSource="{Binding StudentCollection}" DisplayMemberPath="Name" SelectedValuePath="ID">
</autocomplete:SfAutoComplete>

Lets compile and run the app  and it will show the list of students when searching..  By default it suggest data by the starting characters that we are typing.

Image

16 basic data binding.png

Image 18 : Simple SfAutoComplete with Data Binding

So, we have to set the Suggestion mode too. And also we can set the Autocomplete Mode too.

Lets Do it ..

There are 8 main suggestion modes and I’ll select “StartsWith”

17. suggession mode.jpg

Image 19 : Suggestion modes in SfAutoComplete

There are 3 Auto Complete modes and I’ll select “Suggest”.

18 auto complete mode.jpg

Image 20 : Auto Complete modes in SfAutoComplete

Now Lets Customize the AutoComplete control..

now I want to show Student’s image, Name inside the control when searching..

So, I’ll add a data template to the AutoComplete control now.

to do it, we can use the autocomplete:SfAutoComplete.ItemTemplate tag. and we can and we can design the template inside it. in this example I’ll use a Grid View to design the template and below you can see the code. Also I have bind data to the controls which are in the grid.


<StackLayout>
<Label Text="Welcome to Xamarin Forms!" />
<autocomplete:SfAutoComplete DataSource="{Binding StudentCollection}" DisplayMemberPath="Name" SelectedValuePath="ID" SuggestionMode="StartsWith" AutoCompleteMode="Suggest" >
<autocomplete:SfAutoComplete.ItemTemplate>
<DataTemplate>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Image Grid.Row="0" Grid.Column="0" Source="{Binding Image}" WidthRequest="30" VerticalOptions="FillAndExpand"/>
<Label Grid.Row="0" Grid.Column="1" Text="{Binding Name}" HorizontalOptions="FillAndExpand"/>
</Grid>
</DataTemplate>
</autocomplete:SfAutoComplete.ItemTemplate>
</autocomplete:SfAutoComplete>
</StackLayout>

Lets Run the app…

19 custom auto complete.png

Image 21 : Customized SfAutoComplete

It runs successfully…

For more details about SfAutoComplete control please go to this link and you will be able to learn more about it… Including events, Customize the design etc…

https://help.syncfusion.com/xamarin/sfautocomplete/overview

You can have the sample App here…

https://drive.google.com/open?id=0B2gY_8MAQPWnQnZERi03Y0hENk0

References

https://help.syncfusion.com/xamarin/introduction/overview

Thank you !

Xamarin Forms : ListView Height Change Dynamically, using MVVM and also, Solve Empty Space issue

In my previous article, I have explained how to remove the empty space of a List view in Xamarin forms.

To Read the article, Please click the below link.. 🙂

https://xamarinsharp.com/2017/05/16/listview-height-issue-in-xamarin-forms-how-to-solve-it/

In this article, I’ll describe how to dynamically change the List view height using MVVM bindings.

Context..

As a example I have taken a List of “Friends” and when Click the “Add Friend” button, The List view height will change automatically according to the item count. 

Important…

When using Observable Collection, It automatically update the properties of the control that the Items has bind. So, when there are many items in a list, no need to change the height using MVVM and it automatically change the size. This method is useful when there are few items in a List View such as 1-5 items.

cover

Application structure

Here I have created a View (XAML UI and code behind), Model and a ViewModel.

a app

The Friend Model


public class FriendModel
{
public string Name { get; set; }
public string Email { get; set; }
public int ID { get; set; }
}

 

The ViewModel, “MainPageViewModel ” 

Here you can see a command “ChangeListViewSizeCommand” in the view Model and ChangeListViewSize() method has bind to the command.

I have bind it to The “Add New Friend” button in the MainPage view.  When user click the button, it will add a new record to the Friend collection wich is a Observable Collection and then, calculates the height according to the number of items in the collection and Set the value to the “Height” property.

In the setter of the “Height” property, I have called the OnPropertyChanged event. Then the changes of the values will apply to the UI automatically.

Don’t forget to add below namespaces to the View Model.

using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Runtime.CompilerServices;


public class MainPageViewModel : INotifyPropertyChanged
{

public MainPageViewModel()
{
ChangeListViewSizeCommand = new Command(ChangeListViewSize);
}

int count;
int height;
ObservableCollection<FriendModel> friends;

public int Height
{
get
{
return height;
}
set
{
height = value;
OnPropertyChanged();
}
}

public ObservableCollection<FriendModel> Friends
{
get
{
return friends;
}
set
{
friends = value;
Height = (friends.Count * 40) + (friends.Count * 10);
OnPropertyChanged();
}
}

public ICommand ChangeListViewSizeCommand { get; }

void ChangeListViewSize()
{
count = friends.Count + 1;
friends.Add(new FriendModel() { ID = count, Name = string.Format("Friend {0}", count), Email = string.Format("friend{0}@sample.com", count) });
Height = (friends.Count * 40) + (friends.Count * 10);
}

public event PropertyChangedEventHandler PropertyChanged;
void OnPropertyChanged([CallerMemberName]string propertyName = "") =>
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}

The MainPage View XAML code

Here you can see HeightRequest property has bond by Height property of the View model. And the Height of the list view will adjust according to the value of the Height property in the view model.

2 height binding

And to the “Add New Friend” button…

I have Bond the command (“ChangeListViewSizeCommand“).

4 command


<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"              xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"              xmlns:local="clr-namespace:ListViewApp"              x:Class="ListViewApp.MainPage">

    <ScrollView>
        <StackLayout>
            <BoxView HeightRequest="10" HorizontalOptions="FillAndExpand"/>
            <Image Grid.Row="0" Grid.Column="1" HorizontalOptions="Center" VerticalOptions="Center" 		        	 HeightRequest="100" WidthRequest="100" Source = "User.png">
            </Image>
            <Label Text="  Friends " HorizontalOptions="FillAndExpand" BackgroundColor="#C7FCE1" FontSize="Large"/>
            <ListView x:Name="listViewFriends" ItemsSource="{Binding Friends}"  HasUnevenRows="true" SeparatorVisibility="Default"                        VerticalOptions="Fill" MinimumHeightRequest="50" HeightRequest="{Binding Height}">
                <ListView.ItemTemplate>
                    <DataTemplate>
                        <ViewCell>
                            <ViewCell.View>
                                <Grid>
                                    <Grid.RowDefinitions>
                                        <RowDefinition Height="Auto"/>
                                        <RowDefinition Height="Auto"/>
                                    </Grid.RowDefinitions>
                                    <Grid.ColumnDefinitions>
                                        <ColumnDefinition Width="20"/>
                                        <ColumnDefinition Width="Auto"/>
                                        <ColumnDefinition Width="*"/>
                                        <ColumnDefinition Width="20"/>
                                    </Grid.ColumnDefinitions>
                                    <Image Grid.Row="0" Grid.Column="1" Grid.RowSpan="2"                                        WidthRequest="40" HeightRequest="40" Source = "Friend.png">
                                    </Image>
                                    <Label Grid.Row="0" Grid.Column="2" Text="{Binding Name}" FontSize="Medium" TextColor="#065C2B"/>
                                    <Label Grid.Row="1" Grid.Column="2" Text="{Binding Email}" FontSize="Small" TextColor="#6FCF97"/>
                                </Grid>
                            </ViewCell.View>
                        </ViewCell>
                    </DataTemplate>
                </ListView.ItemTemplate>
            </ListView>
            <Button Text="Add New Friend" Command="{Binding ChangeListViewSizeCommand}" TextColor="White" BackgroundColor="#01148E" FontAttributes="Bold" HorizontalOptions="FillAndExpand"/>
            <Button Text="Delete Friend" TextColor="White" BackgroundColor="#B61515" FontAttributes="Bold" HorizontalOptions="FillAndExpand"/>
        </StackLayout>
    </ScrollView>
</ContentPage>

 

Code behind of the View “MainPage “

Here I have bond two friends to the Friends Collection as default values in the GetFriends() method.

In the MainPage constructor, I have bond the MainPageViewModel to the BindingContext of the MainPage and The Friends collection has assigned to the Friends property  of the view model.

3 data binding


using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;

namespace ListViewApp
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class MainPage : ContentPage
{
MainPageViewModel vm = new MainPageViewModel();
public MainPage()
{
InitializeComponent();
vm.Friends = GetFriends();
BindingContext = vm;
}

/// <summary>
/// Get Messages to Message List
/// </summary>
/// <returns></returns>
private ObservableCollection<FriendModel> GetFriends()
{
ObservableCollection<FriendModel> collection = new ObservableCollection<FriendModel>();
try
{
collection.Add(new FriendModel() { ID = 1, Name = "Friend 1", Email = "friend1@sample.com" });
collection.Add(new FriendModel() { ID = 1, Name = "Friend 1", Email = "friend1@sample.com" });
}
catch (Exception)
{
throw;
}
return collection;
}
}

🙂 Then Try it !

Thanks !

ListView Height Issue in Xamarin Forms – How to Solve it ?

Objective

When I was trying to add few items(1-2) to a List View in Xamarin forms inside of a Stack Layout, Its height does not automatically set according to the number of rows and there will be a empty space.

cover2

So I tried different things to solve the issue and finally I found a solution.

Solution

The solution is we have to set the Height of the list view according to the height of number of rows manually in code behind.

And also we can solve it using MVVM dynamically. Please click here to go to the article…

Here are steps to Solve the issue..

  1. Create a new Xamarin forms project with a PCL.
  2. Add a List View in a Stack layout i the MainPage.(But you can do this in your view page)

3 list view unregular code


&lt;?xml version="1.0" encoding="utf-8" ?&gt;
&lt;ContentPage xmlns="http://xamarin.com/schemas/2014/forms"              xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"              xmlns:local="clr-namespace:ListViewApp"              x:Class="ListViewApp.MainPage"&gt;

    &lt;ScrollView&gt;
        &lt;StackLayout&gt;
            &lt;BoxView HeightRequest="10" HorizontalOptions="FillAndExpand"/&gt;
            &lt;Image Grid.Row="0" Grid.Column="1" HorizontalOptions="Center" VerticalOptions="Center" 		        	 HeightRequest="100" WidthRequest="100" Source = "User.png"&gt;
            &lt;/Image&gt;
            &lt;Label Text="  Friends " HorizontalOptions="FillAndExpand" BackgroundColor="#C7FCE1" FontSize="Large"/&gt;
            &lt;ListView x:Name="listViewFriends"  HasUnevenRows="true" SeparatorVisibility="Default" VerticalOptions="Fill"&gt;
                &lt;ListView.ItemTemplate&gt;
                    &lt;DataTemplate&gt;
                        &lt;ViewCell&gt;
                            &lt;ViewCell.View&gt;
                                &lt;Grid&gt;
                                    &lt;Grid.RowDefinitions&gt;
                                        &lt;RowDefinition Height="Auto"/&gt;
                                        &lt;RowDefinition Height="Auto"/&gt;
                                    &lt;/Grid.RowDefinitions&gt;
                                    &lt;Grid.ColumnDefinitions&gt;
                                        &lt;ColumnDefinition Width="20"/&gt;
                                        &lt;ColumnDefinition Width="Auto"/&gt;
                                        &lt;ColumnDefinition Width="*"/&gt;
                                        &lt;ColumnDefinition Width="20"/&gt;
                                    &lt;/Grid.ColumnDefinitions&gt;
                                    &lt;Image Grid.Row="0" Grid.Column="1" Grid.RowSpan="2"                                        WidthRequest="40" HeightRequest="40" Source = "Friend.png"&gt;
                                    &lt;/Image&gt;
                                    &lt;Label Grid.Row="0" Grid.Column="2" Text="{Binding Name}" FontSize="Medium" TextColor="#065C2B"/&gt;
                                    &lt;Label Grid.Row="1" Grid.Column="2" Text="{Binding Email}" FontSize="Small" TextColor="#6FCF97"/&gt;
                                &lt;/Grid&gt;
                            &lt;/ViewCell.View&gt;
                        &lt;/ViewCell&gt;
                    &lt;/DataTemplate&gt;
                &lt;/ListView.ItemTemplate&gt;
            &lt;/ListView&gt;
            &lt;Button Text="Add New Friend" TextColor="White" BackgroundColor="#01148E" FontAttributes="Bold" HorizontalOptions="FillAndExpand"/&gt;
            &lt;Button Text="Delete Friend" TextColor="White" BackgroundColor="#B61515" FontAttributes="Bold" HorizontalOptions="FillAndExpand"/&gt;
        &lt;/StackLayout&gt;
    &lt;/ScrollView&gt;
&lt;/ContentPage&gt;

3.Then Bind data to the List View in the code behind.

(You can Bind data using MVVM. But Here I’ll bind a collection in a simple way).

Here I have created a Model called “Friend” to create the collection of Friends.


using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;

namespace ListViewApp
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class MainPage : ContentPage
{
public MainPage()
{
InitializeComponent();
listViewFriends.ItemsSource = GetFriends();
}

/// &lt;summary&gt;
/// Get Messages to Message List
/// &lt;/summary&gt;
/// &lt;returns&gt;&lt;/returns&gt;
private ObservableCollection&lt;FriendModel&gt; GetFriends()
{
ObservableCollection&lt;FriendModel&gt; collection = new ObservableCollection&lt;FriendModel&gt;();
try
{
collection.Add(new FriendModel() { ID = 1, Name = "Friend 1", Email = "friend1@sample.com" });
collection.Add(new FriendModel() { ID = 1, Name = "Friend 1", Email = "friend1@sample.com" });
listViewFriends.HeightRequest = (40 * collection.Count)+(10* collection.Count);
}
catch (Exception)
{
throw;
}
return collection;
}
}

public class FriendModel
{
public string Name { get; set; }
public string Email { get; set; }
public int ID { get; set; }
}
}

 

4. Then Run the code and you can see a list view with a empty area..

Screenshot_20170516-230919

5. So we have to reduce the Height of the List view.

Lets see the XAML structure of the list view. The List view contains a grid view as the template. And the grid view has 2 rows. It consists of a image with has the row-span=2. That means  normally the height of one item of the List view is equal to the height of the image.

So then I’ll set the

Height(HeightRequest property of ListView) = Number of items * Height of one Item

I have added the code inside of the GetFriends() Method.

4 add a height


private ObservableCollection&lt;FriendModel&gt; GetFriends()
{
ObservableCollection&lt;FriendModel&gt; collection = new ObservableCollection&lt;FriendModel&gt;();
try
{
collection.Add(new FriendModel() { ID = 1, Name = "Friend 1", Email = "friend1@sample.com" });
collection.Add(new FriendModel() { ID = 1, Name = "Friend 1", Email = "friend1@sample.com" });
listViewFriends.HeightRequest = (40 * collection.Count);
}
catch (Exception)
{
throw;
}
return collection;
}

6. Then Run the app again.. And you may see the allocated size is now enough for the list view.

Screenshot_20170516-232247

7. So What Should we do ?

According to that a Item(row) in a List view acquire extra space other than the height of the controls inside it. Normally it may be 10px.

So we have to add it  to the height of the ListView.

HeightRequest = (No.of items * Height of one Item) +(Default space + No.of items)

5 add a height plus padding


/// &lt;summary&gt;
/// Get Messages to Message List
/// &lt;/summary&gt;
/// &lt;returns&gt;&lt;/returns&gt;
private ObservableCollection&lt;FriendModel&gt; GetFriends()
{
ObservableCollection&lt;FriendModel&gt; collection = new ObservableCollection&lt;FriendModel&gt;();
try
{
collection.Add(new FriendModel() { ID = 1, Name = "Friend 1", Email = "friend1@sample.com" });
collection.Add(new FriendModel() { ID = 1, Name = "Friend 1", Email = "friend1@sample.com" });
listViewFriends.HeightRequest = (40 * collection.Count)+(10* collection.Count);
}
catch (Exception)
{
throw;
}
return collection;
}

8. Then Run the code and It will be provide the expected result.

Screenshot_20170516-232610

Thanks !

‘Xamarin.Android.Support.Design 25.3.1’ is not compatible with ‘Xamarin.Forms 2.3.4.231 constraint: Xamarin.Android.Support.Design (= 23.3.0)’. – How to fix it ?

Why ?

When I was trying to update the NuGet Packages for one of my Xamarin projects, I got an error saying “Unable to resolve dependencies.” and the packages wasn’t updated.

The detailed error message is …

Unable to resolve dependencies. ‘Xamarin.Android.Support.Design 25.3.1’ is not compatible with ‘Xamarin.Forms 2.3.4.231 constraint: Xamarin.Android.Support.Design (= 23.3.0)’.

1 error

Image 1 : Error

The reason for the error was…

The Android project of my Xamarin solution has been configured to Compile using Android 6.0(Marshmallow) API 23.3.0 . But I was trying to update the Android packages for Android 7.1 (Nougat) API 25.3.1.

3 current versions

Image 2 : Current Android application properties(Compile using Android 6.0)

So the target compilation version is not compatible with the updating version of Android packages.

How To Fix the Error ?

To fix the error we have to change the target framework for compile to “Android 7.1(Nougat)”.

Here are Steps to change the target compile framework..

2. go to properties

Image 3 : Right Click on Android Project -> Properties

3 current versions

Image 4 : Current Android application properties(Compile using Android 6.0)

4 select api nouget

Image 5 : Change Compile Android Version to Android 7.1 (Nougat)

When Change the target compilation version of Android , Visual Studio will ask you to restart the project to configure itself…

5 restart project

Image 6 : “Yes” to close and reopen

6 lading

Image 7 : App is loading

7 go to nuget

Image 8 : Again go to NuGet package manager to update Android packages

8 download

Image 9 : Select Android Packages v.25.3.1(or the package showing here)

9 accept

Image 10 : Accept to Agree licence and tearms

9 conform update

Image 11 : You can see changes will be happening (the old packages and new packages). Click OK.

10. installing packages

Image 12 : Then the packages will be downloaded and Install Successfully.

Then Re-Build the project and the app will run successfully…

Thanks !

How to Check the App is running for the First time – in Xamarin Forms (Android/iOS/Windows)

Objective

In one of my Xamarin Forms apps, I wanted to check is the app running for the first time after the installation or the app is already installed and according to that Load different pages in the app

 How to Install Xamarin in Visual Studio 2017…

Furthermore,

  1. If the App is running for the first time, I wanted to a Quick Start Guide to the user.
  2. If all has already installed, app will show the Login Form.

pags

Then I looked for a solution and James Montemagno‘s  SettingsPlugin gave me the solution…

If you want to learn more, Click above links to go to GitHub and  MotzCod.es.

How I did it ?

First I went through the Instruction of the above references and I installed the plugin using NuGet..

Here I’ll explain how I did it.. and Here is my project at the beginning.

1-project

1. First Install the Settings Plugin using NuGet packages.. Search  “Xam.Plugins.Settings”

2-download-settings

2. Apply The package to all projects or selected projects.. (But I’m managing the settings from the PCL project) and Install the package..

3-select-all-projects

3. Then Conform the installation..

4-conform-installa-tion

4. When the packages has installed, It will generate a folder which is “Helpers” and a class onside it “Settings.cs” to manage settings.

It will added to all selected projects.

5-helpers-settings

The default Settings class includes below C# code to manage settings..


using Plugin.Settings;
using Plugin.Settings.Abstractions;

namespace FirstTimeUse.Droid.Helpers
{
///
&amp;lt;summary&amp;gt;
/// This is the Settings static class that can be used in your Core solution or in any
/// of your client applications. All settings are laid out the same exact way with getters
/// and setters.
/// &amp;lt;/summary&amp;gt;

public static class Settings
{
private static ISettings AppSettings
{
get
{
return CrossSettings.Current;
}
}

#region Setting Constants

private const string SettingsKey = "settings_key";
private static readonly string SettingsDefault = string.Empty;

#endregion
public static string GeneralSettings
{
get
{
return AppSettings.GetValueOrDefault&amp;lt;string&amp;gt;(SettingsKey, SettingsDefault);
}
set
{
AppSettings.AddOrUpdateValue&amp;lt;string&amp;gt;(SettingsKey, value);
}
}

}
}

To read the more about the Settings class go to:  https://github.com/jamesmontemagno/SettingsPlugin

I’m going to store my value in the SettingsKey property. So I’ll change the default value of the SettingsKey property to “yes”. Which means the app is running for the first time.

6-change-settings-key


private static readonly string SettingsDefault = "yes";

5. Now I’m going to use the Settings in the application..

I’m checking the app status in the App.xaml.cs class. Because the app navigating to the Main page happens in the constructor in App.xaml.cs class.

The default code of the App class is… And there are not properties in this class…


public partial class App : Application
{
public App()
{
InitializeComponent();
MainPage = new MainPage();
}

protected override void OnStart()
{
// Handle when your app starts
}

protected override void OnSleep()
{
// Handle when your app sleeps
}

protected override void OnResume()
{
// Handle when your app resumes
}
}

Now I’ll add a Property to App class to Manage App Settings. The property name is “IsFirstTime” and type is String.

7-add-isfirsttime


///
&amp;lt;summary&amp;gt;
/// Get and Set value to General settings
/// &amp;lt;/summary&amp;gt;

public string IsFirstTime
{
get { return Settings.GeneralSettings; }
set
{
if (Settings.GeneralSettings == value)
return;
Settings.GeneralSettings = value;
OnPropertyChanged();
}
}

6. Now I’ll add another page to use for log in to system if the app has already installed.

Page name is “LoginPage.xaml”.

8-added-2-pages

7. Now Lets Write code in App.xaml.cs to check the app status…

The page is initialize in the constructor of the App class. So I’m going to check the status of the app inside of the constructor.

And Here is the code. In the Settings class, I have set the default value as “yes“. So the app runs for the first time, the value should be “yes“. Then  the MainPage page will open. And when the app ran for the first time, it  sets the “IsFirstTime value to “no“.

Then when the user run the app after the first time, it will load the second page which is Logging Page.

9-check-first-time


public App()
{
InitializeComponent();

// Check is the app running for the first time
if (IsFirstTime == "yes")
{
// if this is the first time, set it to "No" and load the
// Main Page ,which will show at the first time use
IsFirstTime = "no";
MainPage = new FirstTimeUse.MainPage();
}
else
{
// If this is not the first time,
// Go to the login page
MainPage = new FirstTimeUse.LoginPage();
}
}

8. The Build and run the app using emulator. I’m using my Samsung Galaxy J7 as the emulator. And the App was run  successfully.

screenshot_20170219-173522

First time it will open the Main Page

screenshot_20170219-173745

And When I run the app after the first time, It loads the Login page..

 

References…

https://github.com/jamesmontemagno/SettingsPlugin

https://components.xamarin.com/gettingstarted/settingsplugin

 

Thanks !

How to Fix Error “C:\Program Files (Access is Denied)” When Proguard has Enabled while Build a Android app

Why ?

When I was trying to build one of my android apps in “Release” mode to deploy, I got and Error that  “C:\Program Files (Access is Denied)” and the File was “PROGUARD”.

2-errror

Then I looked for a solution to avoid the error.

What is Proguard ?

The Reason For The Error

In the Android project, I have set the Proguard Enabled before I build the app.

The reason for the error is there is a space in the path to the PROGUARD. Proguard is in the Android folder in Program Files (x86) and there is a spaces between “Program Files (x86)”.

C:\Program Files (x86)\Android\android-sdk\tools\proguard

0-program-file-spaces

So PROGUARD may unable to find the path..

So How to Fix This ?

What we have to do is Place the android-sdk folder to a path without spaces..

To do that I created a symbolic Link(sym-link) ..

Here are steps to create a symbolic link..

1 .First we have to download and Install the  Link Shell Extension.

To Download the Link Shell Extension , Click Here .. 

2. After Installed the Extension then we are ready to create the sym-link.

How To Create a Symbolic Link, Click Here…

Here are steps How I created according to my Folder structure..

First I create a Folder in C: drive outside of Program Files x86 which is “AndroidSysLink”. So we have to Link the Android-SDK path to this folder.

First Go to Program Files x86 and Right Click on Android Folder and we can see a new context menu “Pick Link Source”. Then Click it..

1-pick

Then Go back and Select “AndroidSysLink” Folder -> Right Click . Then We can see a new context menu “Drop As” . When we click on it and we will see few options in another context menu. Then Select “Junction”. And then The link will be created.

2-drop-symbolic-link

3. Then We have to change the Android SDK path in Visual Studio.

So go to Tools -> Options -> Xamarin and Click the “change” button inside of the Android SDK location…

Then we can see a dialogue to select the sdk path..

3-existing-sdk-path

4. Go to the Linked folder and copy the path in it..

4-select-new-path

5. Paste the Path in the sdk-path selection dialogue box.

5-new-sdk-path

Then Click OK…

6. Now The Path has changed an Click OK to conform the new SDK path..

6-new-sdk-path

7. Now we are ready to release the app. But before Build the app recheck the configuration in properties.

First Verify Target Android versions..

0-selectandroid-versions

Make Sure the Confutation has set to “Release” and Proguard is Enabled..

1-enable-proguard

8. Then Build The app in Release Mode..

The app will build successfully..

3-build-success

9. Now we are ready to Archive the Android App.

Right Click on the Android project and click “Archive“…

4-archieve

We can see Archiving Progress…

5-archieving

We can see a Settings I con with a Green icon when the app has archived successfully and in the bottom of the dialogue we can see build information.

6-archieved-successfully

Click the “Open” folder and the created .apk file will see in that folder.

7-open-the-path

References…

https://developer.xamarin.com/guides/android/deployment,_testing,_and_metrics/publishing_an_application/part_1_-_preparing_an_application_for_release/

https://developer.xamarin.com/guides/android/application_fundamentals/cpu_architectures/

https://developer.xamarin.com/guides/android/deployment,_testing,_and_metrics/proguard/

https://www.howtogeek.com/howto/16226/complete-guide-to-symbolic-links-symlinks-on-windows-or-linux/

http://schinagl.priv.at/nt/hardlinkshellext/linkshellextension.html

https://forums.xamarin.com/discussion/45210/enable-proguard-error-c-program-files-access-is-denied

Thanks !