在CALayer中对自定义属性进行动画处理

我正在尝试让动画在CALayer中的自定义属性上工作。

I'm trying to get animation working on a custom property in a CALayer.

但是我只是无法弄清楚如何使其正常工作。 。密钥 myCounter永远不会发送到NeedsDisplayForKey。我缺少一些步骤吗？以下是我正在测试的课程，我将该课程添加到其他位置的图层中。有没有人拥有使用单点触控进行动画处理的自定义属性？

But I just just am not able to figure out how to get this working correctly. The key "myCounter" is never sent to NeedsDisplayForKey. Are there some steps I'm missing? Below is the class I'm testing which I add to a layer elsewhere. Has anyone got a custom property to animate using monotouch?

    public class TestProperty : CALayer
    {
    //this line updated based on feedback below**********
        public uint myCounter { [Export ("myCounter")] get; [Export setMyCounter:")]  set; }


    public TestProperty ()
    {
        CABasicAnimation anim = CABasicAnimation.FromKeyPath("myCounter");
        anim.From = NSNumber.FromInt32(1);
        anim.To = NSNumber.FromInt32(10);
        anim.Duration = 1.0f;
        anim.RepeatCount = float.MaxValue;
        anim.AutoReverses = true;
        this.AddAnimation(anim,null);
    }

    [Export ("needsDisplayForKey:")]
    static bool NeedsDisplayForKey (NSString key)
    {
        Console.WriteLine("{0}", key.ToString());

        if(key.Equals("myCounter"))
        {
            return true; //never gets here
        }
        else
            return false;

    }
    }