A Complete Guide - .NET MAUI Using DependencyService and IPlatformService

Prerequisites

1. .NET MAUI Installed: Ensure you have the latest version of .NET MAUI installed in your Visual Studio.
2. Basic Knowledge: Familiarity with C#, XAML, and .NET MAUI is helpful.

Step 1: Create a New .NET MAUI Project

1. Open Visual Studio.
2. Create a New Project:
   • Go to File > New > Project.
   • Select MAUI App (.NET 6+/.NET Standard 2.0).
   • Click Next.
3. Configure the Project:
   • Enter your project name, e.g., MauiDependencyServiceExample.
   • Choose a location and click Create.
4. Solution Structure:
   • Your solution will contain platform-specific projects (e.g., MauiDependencyServiceExample.Android, MauiDependencyServiceExample.iOS, etc.).

Step 2: Define the Interface IPlatformService

Create an interface that will define the platform-specific functionality you want to expose. In this example, we'll create a simple service to show a platform-specific message.

1. Add a New Interface:
   • Right-click on the MauiDependencyServiceExample (Shared) project.
   • Go to Add > New Item.
   • Select Interface and name it IPlatformService.cs.
2. Define the Method:

   using System.Threading.Tasks;
   
   namespace MauiDependencyServiceExample
   {
       public interface IPlatformService
       {
           Task ShowPlatformMessage(string message);
       }
   }
   

Step 3: Implement IPlatformService for Android

1. Add a New Class:
   • Navigate to the MauiDependencyServiceExample.Android project.
   • Right-click the project and select Add > New Item.
   • Choose Class and name it PlatformServiceAndroid.cs.
2. Implement the Interface:

   using Android.App;
   using Android.Widget;
   using MauiDependencyServiceExample;
   using System.Threading.Tasks;
   
   [assembly: Xamarin.Forms.Dependency(typeof(PlatformServiceAndroid))]
   namespace MauiDependencyServiceExample.Droid
   {
       public class PlatformServiceAndroid : IPlatformService
       {
           public Task ShowPlatformMessage(string message)
           {
               RunOnUiThread(() =>
               {
                   Toast.MakeText(Application.Context, message, ToastLength.Short).Show();
               });
               return Task.CompletedTask;
           }
   
           private void RunOnUiThread(Action action)
           {
               Application.SynchronizationContext.Post(_ => action?.Invoke(), null);
           }
       }
   }
   

Step 4: Implement IPlatformService for iOS

1. Add a New Class:
   • Navigate to the MauiDependencyServiceExample.iOS project.
   • Right-click the project and select Add > New Item.
   • Choose Class and name it PlatformServiceiOS.cs.
2. Implement the Interface:

   using MauiDependencyServiceExample;
   using UIKit;
   using System.Threading.Tasks;
   
   [assembly: Xamarin.Forms.Dependency(typeof(PlatformServiceiOS))]
   namespace MauiDependencyServiceExample.iOS
   {
       public class PlatformServiceiOS : IPlatformService
       {
           public Task ShowPlatformMessage(string message)
           {
               UIKit.UIThread.RunBackground(() =>
               {
                   UIKit.UIThread.RunOnMain(() =>
                   {
                       var alertController = UIAlertController.Create(null, message, UIAlertControllerStyle.Alert);
                       alertController.AddAction(UIAlertAction.Create("OK", UIAlertActionStyle.Default, null));
                       UIApplication.SharedApplication.KeyWindow.RootViewController.PresentViewController(alertController, true, null);
                   });
               });
               return Task.CompletedTask;
           }
       }
   }
   

Step 5: Use DependencyService in the Shared Code

Now, let's use DependencyService to invoke the platform-specific method from the shared code.

1. Modify MainPage.xaml:

   <?xml version="1.0" encoding="utf-8" ?>
   <ContentPage xmlns="
                xmlns:x="
                x:Class="MauiDependencyServiceExample.MainPage"
                Title="Maui DependencyService Example">
   
       <StackLayout Padding="20">
           <Label Text="Welcome to Maui!" 
                  HorizontalTextAlignment="Center" 
                  FontSize="24" 
                  Margin="0,0,0,20"/>
   
           <Button Text="Show Platform Message" 
                   Clicked="OnShowPlatformMessageClicked" 
                   HorizontalOptions="CenterAndExpand" 
                   BackgroundColor="#007AFF" 
                   TextColor="White"/>
       </StackLayout>
   </ContentPage>
   

2. Modify MainPage.xaml.cs:

   using MauiDependencyServiceExample;
   using Microsoft.Maui.Controls;
   using System.Threading.Tasks;
   
   namespace MauiDependencyServiceExample
   {
       public partial class MainPage : ContentPage
       {
           public MainPage()
           {
               InitializeComponent();
           }
   
           private async void OnShowPlatformMessageClicked(object sender, System.EventArgs e)
           {
               // Resolve the platform-specific service
               var platformService = DependencyService.Get<IPlatformService>();
   
               // Invoke the platform-specific method
               await platformService.ShowPlatformMessage("Hello from .NET MAUI!");
           }
       }
   }
   

Step 6: Run the Application

1. Select a Platform: Choose the platform you want to run the app on (e.g., Android, iOS).
2. Deploy the App:
   • Android: Connect an Android device or use an emulator.
   • iOS: Use a Mac with Xcode or an iPhone/iPad.
3. Run the App: Click the green play button in Visual Studio.

Expected Output:

• Android: A toast message saying "Hello from .NET MAUI!" will appear.
• iOS: An alert dialog with the message "Hello from .NET MAUI!" will be displayed.

Summary

You have successfully created a .NET MAUI application that uses DependencyService to invoke platform-specific functionality through an interface (IPlatformService). This approach allows you to write shared code while accessing native capabilities on each platform.

Additional Resources

• Xamarin.Forms DependencyService Documentation
• .NET MAUI Documentation
• Xamarin.Forms vs .NET MAUI Comparison