Migrate Xamarin.Essentials code in .NET for Android and .NET for iOS apps

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net8.0-android</TargetFramework>
    ...
    <UseMauiEssentials>true</UseMauiEssentials>
  </PropertyGroup>
</Project>

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net8.0-ios</TargetFramework>
    ...
    <UseMauiEssentials>true</UseMauiEssentials>
  </PropertyGroup>
</Project>

In any Activity that's launched, you must call the Platform.Init method, which is in the Microsoft.Maui.ApplicationModel namespace, from the OnCreate method:

using Android.Content.PM;
using Android.Runtime;
using Microsoft.Maui.ApplicationModel;

namespace MyAndroidApp;

[Activity(Label = "@string/app_name", MainLauncher = true)]
public class MainActivity : Activity
{
    protected override async void OnCreate(Bundle? savedInstanceState)
    {
        base.OnCreate(savedInstanceState);
        Platform.Init(this, savedInstanceState);
        // ...
    }
}

The Platform.Init method requires an Application argument, or a Activity argument and a Bundle argument.

In your AppDelegate class, you must call the Platform.Init method, which is in the Microsoft.Maui.ApplicationModel namespace, from the FinishedLaunching method:

using Microsoft.Maui.ApplicationModel;

namespace MyiOSApp;

[Register("AppDelegate")]
public class AppDelegate : UIApplicationDelegate
{
    public override UIWindow? Window
    {
        get;
        set;
    }

    public override bool FinishedLaunching(UIApplication application, NSDictionary launchOptions)
    {
        // create a new window instance based on the screen size
        Window = new UIWindow(UIScreen.MainScreen.Bounds);

        // create a UIViewController with a single UILabel
        var vc = new UIViewController();
        // ...
        Window.RootViewController = vc;

        Platform.Init(() => vc);

        // make the window visible
        Window.MakeKeyAndVisible();

        return true;
    }
}

The Platform.Init method requires a Func<UIKit.UIViewController argument.

To access the current Context or Activity for the running app:

var context = Platform.AppContext;

// Current Activity or null if not initialized or not started.
var activity = Platform.CurrentActivity;

If there's a situation where the Activity is needed, but the app hasn't fully started, call the WaitForActivityAsync method:

var activity = await Platform.WaitForActivityAsync();

To handle runtime permission requests, override the OnRequestPermissionsResult method in every Activity and call the Platform.OnRequestPermissionsResult method from it:

public override void OnRequestPermissionsResult(int requestCode, string[] permissions, Permission[] grantResults)
{
    Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);
    base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
}

In addition to getting the current Activity, you can also register for lifecycle events:

protected override void OnCreate(Bundle bundle)
{
    base.OnCreate(bundle);
    Platform.Init(this, bundle);
    Platform.ActivityStateChanged += Platform_ActivityStateChanged;
}

protected override void OnDestroy()
{
    base.OnDestroy();
    Platform.ActivityStateChanged -= Platform_ActivityStateChanged;
}

void Platform_ActivityStateChanged(object sender, ActivityStateChangedEventArgs e) =>
    Toast.MakeText(this, e.State.ToString(), ToastLength.Short).Show();

Activity states are:

• Created
• Resumed
• Paused
• Destroyed
• SaveInstanceState
• Started
• Stopped

For example, to handle app actions, override the PerformActionForShortcutItem method in your AppDelegate class and call the Platform.PerformActionForShortcutItem method from it:

public override void PerformActionForShortcutItem(UIApplication application, UIApplicationShortcutItem shortcutItem, UIOperationHandler completionHandler)
{
    Platform.PerformActionForShortcutItem(application, shortcutItem, completionHandler);
}