Xamarin.Forms.Background (Background plugin for Xamarin.Forms)

A plugin library to simplify Backgrounding in Xamarin.Forms.

Get Started

Ever wonder how facebook and twitter process there background to fetch a new content? And it looks so slick that when you refresh it was snappy and smooth, Making the user believed that the content is refreshed and updated in a snap when in fact it was done in the background.

The secret behind it was the background service. And so we have created Xamarin.Forms.Background to make our backgrounding task be simple and maintenable.

Build & Test Status

Setup

NuGet: Xamarin.Forms.Background
Install into ALL of your projects, including client projects.
Initialize BackgroundAggregator in each platform project.

For Android

You call the "Init" method before all libraries initialization in MainActivity class.

public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
{
    protected override void OnCreate(Bundle bundle)
    {
        BackgroundAggregator.Init(this);
        
        base.OnCreate(bundle);
        ....// Code for init was here
    }
}

For iOS

You call the "Init" method before all libraries initialization in FinishedLaunching method in FormsApplicationDelegate class.

public partial class AppDelegate : global::Xamarin.Forms.Platform.iOS.FormsApplicationDelegate
{
    public override bool FinishedLaunching(UIApplication app, NSDictionary options)
    {
         BackgroundAggregator.Init(this);
         
        ....// Code for init was here
         return base.FinishedLaunching(app, options);
    }
}

For macOS

You call the "Init" method before all libraries initialization in DidFinishLaunching method in FormsApplicationDelegate class.

public partial class AppDelegate : global::Xamarin.Forms.Platform.MacOS.FormsApplicationDelegate
{
    public override void DidFinishLaunching(NSNotification notification)
    {
        BackgroundAggregator.Init(this);
        Forms.Init();
        LoadApplication(new App());
        base.DidFinishLaunching(notification);
    }
}

For Tizen

You call the "Init" method before all libraries initialization in OnCreate method in FormsApplication class.

class Program : global::Xamarin.Forms.Platform.Tizen.FormsApplication
{
    protected override void OnCreate()
    {
        base.OnCreate();
        BackgroundAggregator.Init(this);
        LoadApplication(new Sample.App());
    }

    static void Main(string[] args)
    {
        var app = new Program();
        global::Xamarin.Forms.Platform.Tizen.Forms.Init(app);
        app.Run(args);
    }
}

For Gtk

You call the "Init" method before all libraries initialization in Main method in MainClass class.

class MainClass
{
    [STAThread]
    public static void Main(string[] args)
    {
        Gtk.Application.Init();
        Forms.Init();
        
        BackgroundAggregator.Init();

        var app = new App();
        var window = new FormsWindow();
        window.LoadApplication(app);
        window.SetApplicationTitle("Game of Life");
        window.Show();

        Gtk.Application.Run();
    }
}

For UWP

First, You call the "Init" method before all libraries initialization in MainPage class.

public sealed partial class MainPage
{
    public MainPage()
    {
        this.InitializeComponent();
        
        BackgroundAggregator.Init(this);
        
        LoadApplication(new SampleBackground.App(new UwpInitializer()));
    }
}

Then you put the line "BackgroundAggregatorService.Instance.Start()" in OnBackgroundActivated method under App.cs of UWP project.

protected override void OnBackgroundActivated(BackgroundActivatedEventArgs args)
{
    base.OnBackgroundActivated(args);
    BackgroundAggregatorService.Instance.Start();
}

Create Background Task

You will have to inherit IBackgroundTask interface in which you will supply and implement the interval and StartJob.

public class SomeBackgroundWork : IBackgroundTask
{
    public SomeBackgroundWork()
    {
    }

    public Task StartJob()
    {
        // YOUR CODE HERE

        return;
    }
}

Register Background Task

After you have implemented the Background Task you will need to register it to Background Aggregator Service. We define it on OnStart() method under App.cs.

protected override void OnStart()
{
    //Register Background Tasks
    BackgroundAggregatorService.Add(() => new SomeBackgroundWork());
    BackgroundAggregatorService.Add(() => new OtherBackgroundWork());

    //Start the background service
    BackgroundAggregatorService.StartBackgroundService();
}

Quirks and Limitation

Keep in mind that the plugin was not design to communicate with UI thread, one way of dealing the transfer of information is through storage (e.g. Sqlite or Settings plugin). Our sample project is using Monkey-Cache storage.

Starting with Android Oreo it has already introduced the background execution limits similar to iOS background time limits assuming the app is in background mode or app is closed or minimized, as discuss on this article.

UWP backgrounding uses In-Process backgrounding which is a bit less resilient than the Out-Process, however In-Process provides simplier approach and this is why we intend to support this platform using this approach.

For recently supported Gtk Mac and Tizen are very straightforward it doesn't require native backgrounding, however it runs the task on a separate thread to immitate backgrounding process.

For more info about Backgrounding in Android please check the link HERE.

For more info about Backgrounding in iOS please check the link HERE.

For more info about Backgrounding in UWP please check the link HERE.

That's it

You can now run your app that runs your Background Tasks in the Background Service. We have provided a few good samples to for you to dig in.

Our Sample

We have created a sample app that has 3 tasks in the background that get an RSS feed from news outlet like BBC News, CNN News and Washington Post.

Platform Supported

Platform	Version
Xamarin.iOS	iOS 7+
Xamarin.Mac	All
Xamarin.Android	API 15+
Windows 10 UWP	10+
Tizen	4.0+
Gtk	All
.NET Standard	2.0+

nblockchain/XamarinFormsBackground