Xamarin main method or equivalent

Question

I'm new to Xamarin and I'm looking for an entry point like a main() method. Also, I have a data storage (i.e. model) class, which constantly receives data from a web socket and shall be accessible from throughout the application (i.e. from multiple ViewModels). Where can I put significant and central classes like these? Would you put these in a static class?

Also: Is there something like a main-loop which is responsible for handling tasks and events?

I'd be very grateful for a generic/primer overview of all the "entry points" within a Xamarin application.

Answer 1

Each platform has their own main() like methods

• Android: MainActivity.OnCreate()
• iOS: AppDelegate.FinishedLaunching(UIApplication app, NSDictionary options)
• UWP: App.OnLaunched(LaunchActivatedEventArgs e)

on Xamarin.Forms applications all those platforms instantiates App class and sets the MainPage.

You should use App.OnStart() method if you want to do for BL.

Answer 2

If you for example create a Cross Platform Mobile App in Visual Studio 2017 you will already get a scaffold. The data layer is located in the 'Services' Folder.

I would consider the "App.xaml" file as your entry point.

   public partial class App : Application
{
    //TODO: Replace with *.azurewebsites.net url after deploying backend to Azure
    public static string AzureBackendUrl = "http://localhost:5000";
    public static bool UseMockDataStore = false;
    public static bool UseEntityFramework = true;

    public App()
    {
        InitializeComponent();

        if (UseMockDataStore)
            DependencyService.Register<MockDataStore>();
        else if (UseEntityFramework)
            DependencyService.Register<SqLiteDataStore>();
        else
            DependencyService.Register<AzureDataStore>();

        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
    }
}