Unrecognized selector when use member method as delegate on iOS

IDE: VS 2015
Version: 8.4.96.2027
Target (If relevant): iOS
Description:

iOSTest2.zip (107.5 KB)

    public class TestClass {

    private int mTagValue;

    public TestClass(int tag){
        mTagValue = tag;
    }

    public void doSth() {
        NSLog("doSth: " + mTagValue);
    }
}

[UIApplicationMain, IBObject]
class AppDelegate : IUIApplicationDelegate
{
    public UIWindow window { get; set; }

    // Ensure the obj won't be deallocated
    private TestClass mRef;

    public BOOL application(UIApplication application) didFinishLaunchingWithOptions(NSDictionary launchOptions)
    {
        window = new UIWindow(UIScreen.mainScreen().bounds);
        window.rootViewController = new UIViewController withNibName(null) bundle(null);
        window.makeKeyAndVisible();
        
        mRef = new TestClass(999);

        // Exception: Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[TestClass doSth]: unrecognized selector sent to instance 0x7fcd62e01210'
        dispatch_async(dispatch_get_main_queue(), mRef.doSth);

        return true;
    }

Thanks, logged as bugs://75851

bugs://75851 got closed with status fixed.

Logged as bugs://i63802.

bugs://i63802 was closed as fixed.