How to use CPNowPlayingRepeatButton with action handler

[janwiebe-jump]

It looks like the CarPlay button constructors are not correctly bound, because the constructor that takes an Action<CPNowPlayingButton> is not available.

Steps to Reproduce

1. Add a using to CarPlay
2. Try to create a CPNowPlayingRepeatButton with the Action parameter

new CPNowPlayingRepeatButton((h) => {});

Expected Behavior

Since the base class CPNowPlayingButton exposes the constructor with the handler (), the implementations should do it as well.

• CPNowPlayingRepeatButton
• CPNowPlayingPlaybackRateButton
• CPNowPlayingMoreButton
• CPNowPlayingAddToLibraryButton
• CPNowPlayingShuffleButton

Is there a workaround possible by using the objc_msgSend?

Actual Behavior

The constructor that takes an action (like CPNowPlayingImageButton does) are not exposed

Environment

Version information

Microsoft Visual Studio Community 2022
Version 17.2.3
VisualStudio.17.Release/17.2.3+32526.322
Microsoft .NET Framework
Version 4.8.04161

Installed Version: Community

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Razor (ASP.NET Core)   17.0.0.2218101+885a343b00bcab620a90c1550c37dafd730ce984
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SQL Server Data Tools   17.0.62204.01010
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Xamarin.iOS and Xamarin.Mac SDK   15.10.0.1 (568bdb24e)
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Build Logs

Example Project (If Possible)

[rolfbjarne]

Is there a workaround possible by using the objc_msgSend?

I think this should work: https://gist.github.com/rolfbjarne/4f1959d61b9cbc1b9fb3138fe7e15c92

[janwiebe-jump]

Hi @rolfbjarne
Thanks for your response. Unfortunately, it doesn't work:
I get an exception:

Hovering descriptor->Target says expression not supported.

Do you have an idea how to fix this?

Stacktrace:

Unhandled managed exception: Specified cast is not valid. (System.InvalidCastException)
  at (wrapper castclass) System.Object.__castclass_with_cache(object,intptr,intptr)
  at ObjCRuntime.Trampolines.SDActionArity1V29.Invoke (System.IntPtr block, System.IntPtr obj) [0x00008] in D:\Projects\app-name\app\app-name\app-name.iOS\CarPlay\CarPlayHelper.cs:68 
  at (wrapper native-to-managed) ObjCRuntime.Trampolines.SDActionArity1V29.Invoke(intptr,intptr)
  at (wrapper managed-to-native) UIKit.UIApplication.UIApplicationMain(int,string[],intptr,intptr)
  at UIKit.UIApplication.Main (System.String[] args, System.Type principalClass, System.Type delegateClass) [0x0003b] in /Users/builder/azdo/_work/1/s/xamarin-macios/src/UIKit/UIApplication.cs:85 
  at app-name.iOS.Application.Main (System.String[] args) [0x00001] in D:\Projects\app-name\app\app-name\app-name.iOS\Main.cs:17 

[rolfbjarne]

@janwiebe-jump you could add some debugging to get more info about the actual type of the delegate:

static unsafe void Invoke (IntPtr block, IntPtr obj) {
	var descriptor = (BlockLiteral *) block;
	var del2 = descriptor->Target;
	if (!(del2 is global::System.Action<global::CarPlay.CPNowPlayingButton> del)) {
		throw new InvalidCastException ($"Unable to cast from {del2.GetType ().AssemblyQualifiedName} to {typeof (global::System.Action<global::CarPlay.CPNowPlayingButton>).AssemblyQualifiedName}");
	}
	if (del != null)
		del ( Runtime.GetNSObject<CarPlay.CPNowPlayingButton> (obj)!);
}