Method 'UIKit.UIApplication.Main' is obsolete: Use the overload with 'Type' instead of 'String' parameters for type safety

Question

After upgrade my Xamarin.Forms version to 5.0.0.2244, I'm getting the following warning in Main.cs file inside my iOS project:

Method UIKit.UIApplication.Main is obsolete: Use the overload with Type instead of String parameters for type safety.

This my Main.cs file:

using UIKit;

namespace LindeGctMobileApplication.iOS
{
    public class Application
    {
        private static void Main(string[] args)
        {
            UIApplication.Main(args, null, "AppDelegate"); // << warning
        }
    }
}

What do I need to change to remove this warning?

Effeminate

Answer 1

Class reference through a string is now deprecated. You need to change this line:

UIApplication.Main(args, null, "AppDelegate");

to this:

UIApplication.Main(args, null, typeof(AppDelegate));

In that way, you explicitly inform the type of the class.

Effeminate

As a hint: If I use the new approach the app crashes, when taking a picture with the CrossMedia plugin. The exception is: There's no current active window (System.InvalidOperationException) – Thermit

This is a good bug to investigate. Do you know why? – Sonnysonobuoy

The plugin is not maintaned anymore ... One should use the one from Xamarin.Essentials. I didn't investigate more into this. – Thermit

Answer 2

Method UIKit.UIApplication.Main is obsolete: Use the overload with Type instead of String parameters for type safety.

This issue will be fixed by updating the Main.cs file from:

 UIApplication.Main(args, null, "AppDelegate");

to:

UIApplication.Main(args, null, typeof(AppDelegate));

iOS API 12

public static void Main (string[] args, string principalClassName, string delegateClassName);

The above methods excepts to receive the string type.

iOS API 17

public static void Main (string[] args, Type? principalClassName, Type? delegateClassName);

Now the API is excepting to pass the Type instead of string. Still both are available for use

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