自定义LeftBarButtonItem没有响应触摸？

Question

我有以下自定义大小的LeftBarButtonItem，有时它没有响应我的触摸，例如60％的响应时间

        UIImage yourBackImage = UIImage.FromBundle("back-button");
        var newSize = new CGSize(20, 20);
        UIGraphics.BeginImageContextWithOptions(newSize, false, 0.0f);
        yourBackImage.Draw(new CGRect(0, 0, newSize.Width, newSize.Height));
        UIImage resizeImage = UIGraphics.GetImageFromCurrentImageContext();
        UIGraphics.EndImageContext();

        UIButton backButton = new UIButton(UIButtonType.System);
        backButton.SetImage(resizeImage.ImageWithRenderingMode(UIImageRenderingMode.AlwaysOriginal), UIControlState.Normal);
        backButton.Frame = new CoreGraphics.CGRect(0, 0, 44, 44);
        backButton.TouchUpInside += delegate
        {
            DetailController dc = new DetailController();
            NavigationController.PushViewController(dc, false);
        };
        backButton.ImageEdgeInsets = new UIEdgeInsets(top: 0, left: -13.0f, bottom: 0, right: 13.0f);

        backButton.WidthAnchor.ConstraintEqualTo(44.0f).Active = true;
        backButton.HeightAnchor.ConstraintEqualTo(44.0f).Active = true;
        NavigationItem.LeftBarButtonItem = new UIBarButtonItem(backButton);