MAUI: Dependency injection is not working

Question

I have a dependency injection in my project for getting the device unique id. It is working fine in my xamarin forms project, but when I add it on my MAUI project the result is blank.

My code

IDevice

public interface IDevice
{
    string GetIdentifier();
}

AndroidDevice

public class AndroidDevice : IDevice
{
    public string GetIdentifier()
    {
        return Android.Provider.Settings.Secure.GetString(Android.App.Application.Context.ContentResolver, Android.Provider.Settings.Secure.AndroidId);
    }
}

IOSDevice

public class IOSDevice : IDevice
{
    [DllImport("/System/Library/Frameworks/IOKit.framework/IOKit")]
    private static extern uint IOServiceGetMatchingService(uint masterPort, IntPtr matching);

    [DllImport("/System/Library/Frameworks/IOKit.framework/IOKit")]
    private static extern IntPtr IOServiceMatching(string s);

    [DllImport("/System/Library/Frameworks/IOKit.framework/IOKit")]
    private static extern IntPtr IORegistryEntryCreateCFProperty(uint entry, IntPtr key, IntPtr allocator, uint options);

    [DllImport("/System/Library/Frameworks/IOKit.framework/IOKit")]
    private static extern int IOObjectRelease(uint o);

    public string GetIdentifier()
    {
        string serial = string.Empty;
        uint platformExpert = IOServiceGetMatchingService(0, IOServiceMatching("IOPlatformExpertDevice"));
        if (platformExpert != 0)
        {
            NSString key = (NSString)"IOPlatformSerialNumber";
            IntPtr serialNumber = IORegistryEntryCreateCFProperty(platformExpert, key.Handle, IntPtr.Zero, 0);
            if (serialNumber != IntPtr.Zero)
            {
                serial = NSString.FromHandle(serialNumber);
                //serial = UIDevice.CurrentDevice.IdentifierForVendor.ToString();
            }
            IOObjectRelease(platformExpert);
        }
        return serial;
    }
}

On this thread I have seen adding the dependency service to DI services.

.Services.AddTransient<IGetDeviceInfo, GetDeviceInfo>();

But when I added that, the AndroidDevice class is not found error is showing like the below screenshot.

The type or namespace name 'AndroidDevice' could not be found (are you missing a using directive or an assembly reference?)

Answer 1

Hello,

If you want to invoke specific platform code, you can use Conditional compilation then execute these sepcific code directly in MAUI.

For example, you create a class that called GetDevice.cs like following code in the MAUI. You can use different namespaces for iOS and Android platform code, then execute the specific code that wrap Conditional compilation.

#if ANDROID

using static Android.Provider.Settings;

#elif IOS

using Foundation;
using System.Runtime.InteropServices;
#endif


namespace MauiApp1;

public  class GetDevice
{
    public  string GetIdentifier()
    {
        string Identifier = "";

#if ANDROID
        Identifier= Secure.GetString(Microsoft.Maui.ApplicationModel.Platform.CurrentActivity.ContentResolver, Secure.AndroidId);


#elif IOS
        [DllImport("/System/Library/Frameworks/IOKit.framework/IOKit")]
         static extern uint IOServiceGetMatchingService(uint masterPort, IntPtr matching);

       [DllImport("/System/Library/Frameworks/IOKit.framework/IOKit")]
         static extern IntPtr IOServiceMatching(string s);

       [DllImport("/System/Library/Frameworks/IOKit.framework/IOKit")]
         static extern IntPtr IORegistryEntryCreateCFProperty(uint entry, IntPtr key, IntPtr allocator, uint options);

       [DllImport("/System/Library/Frameworks/IOKit.framework/IOKit")]
         static extern int IOObjectRelease(uint o);
        string serial = string.Empty;
            uint platformExpert = IOServiceGetMatchingService(0, IOServiceMatching("IOPlatformExpertDevice"));
            if (platformExpert != 0)
            {
                NSString key = (NSString)"IOPlatformSerialNumber";
                IntPtr serialNumber = IORegistryEntryCreateCFProperty(platformExpert, key.Handle, IntPtr.Zero, 0);
                if (serialNumber != IntPtr.Zero)
                {
                    serial = NSString.FromHandle(serialNumber);
                    //serial = UIDevice.CurrentDevice.IdentifierForVendor.ToString();
                }
                IOObjectRelease(platformExpert);
            }
            Identifier=serial;
#endif
       return Identifier;

   }
}

For example, When you want to get Identifier in the button click event. You can initialize this GetDevice.cs and get value directly.

  private async void Button_Clicked(object sender, EventArgs e)
    {
#if ANDROID || IOS
        GetDevice getDevice=  new GetDevice();
        var res=getDevice.GetIdentifier();

#endif
   }

Best Regards,

Leon Lu

---

If the answer is the right solution, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.