逐渐刷UIView XAMARIN IOS

Question

我正在做一个项目，我不能使用xamarin.forms或故事板。我想滑动一个UIView，让它逐渐消失(在我滑动之后，如果你知道我想说什么的话)。我可以刷卡，我用的是SwipeGesture，但是我怎么才能让刷卡变得生动起来呢？在我刷卡的时候慢慢褪色吗？

代码：

      UIView testeS = new UIView(new CGRect(0, 0, 5, UIScreen.MainScreen.Bounds.Height));
            testeS.BackgroundColor = UIColor.Clear;
            Add(testeS);
            UISwipeGestureRecognizer swipeRight = new UISwipeGestureRecognizer(OnSwipeRight);
            swipeRight.Direction = UISwipeGestureRecognizerDirection.Right;
            testeS.AddGestureRecognizer(swipeRight);


            UISwipeGestureRecognizer swipeLeft = new UISwipeGestureRecognizer(OnSwipeLeft);
            swipeLeft.Direction = UISwipeGestureRecog



        private void OnSwipeRight()
        {
            Add(tab);
        }

        private void OnSwipeLeft()
        {
            tab.RemoveFromSuperview();
        }

谢谢

Answer 1

我不确定你所说的“消失”是指淡出(不透明/Alpha)还是你想让视图改变宽度直到它消失。

滑动手势识别器只有在你做一个滑动手势时才能感知，它不能“跟随”你的触摸。为此，您需要子类UIView并实现touches方法，例如BeginTouches等。下面的UIView子类将观察触摸(仅限单点触摸，默认情况下视图上不启用多点触摸)，并在触摸移动时调整视图的宽度：

public class SwipeView : UIView
{
    nfloat initialTouchXLocation;
    CGRect initialFrame;

    public SwipeView(CGRect rect) : base(rect)
    {
        initialFrame = rect;
    }

    public override void TouchesBegan(NSSet touches, UIEvent evt)
    {
        base.TouchesBegan(touches, evt);

        initialTouchXLocation = touches.ToArray<UITouch>()[0].LocationInView(this).X;
    }

    public override void TouchesMoved(NSSet touches, UIEvent evt)
    {
        base.TouchesMoved(touches, evt);

        nfloat newTouchXLocation = touches.ToArray<UITouch>()[0].LocationInView(this).X;

        nfloat newWidth = (newTouchXLocation - initialTouchXLocation) + initialFrame.Width;
        if (newWidth < 5)
            newWidth = 5; // keeps the view from getting too narrow to touch
        Frame = new CGRect(initialFrame.X, initialFrame.Y, newWidth, initialFrame.Height);
    }

    public override void TouchesCancelled(NSSet touches, UIEvent evt)
    {
        base.TouchesCancelled(touches, evt);

        initialFrame = this.Frame;
    }

    public override void TouchesEnded(NSSet touches, UIEvent evt)
    {
        base.TouchesEnded(touches, evt);

        initialFrame = this.Frame;
    }
}

然后只需添加此视图，而不是常用的UIView：

SwipeView testeS = new SwipeView(new CGRect(0, 0, 5, UIScreen.MainScreen.Bounds.Height));
testeS.BackgroundColor = UIColor.Red;
Add(testeS);