无法访问 UIPanGestureRecognizer 中的对象

Question

我正在使用以编程方式生成的对象制作贝塞尔动画。对象的数量可能大于 100。这些对象也会对触摸做出响应。

动画效果很好。现在我想让一些对象可以拖动。

但是，我无法访问 UIPanGestureRecognizer 函数中的各个对象。我假设我在调用类/子类时做错了什么，但想不出来..

我查看的教程为屏幕上的每个动画对象提供了 IBOutlets 或专用类变量。我确实有可能在 FOR 循环中生成大量对象。

你有什么建议？

func panning(pan: UIPanGestureRecognizer) {

    self.view.bringSubviewToFront(pan.view!)
    var translation  = pan.translationInView(self.view)

    pan.view.center = CGPointMake(pan.view.center.x + translation.x, pan.view.center.y + translation.y)

    pan.setTranslation(CGPointZero, inView: self.view)


        let panGesture = UIPanGestureRecognizer(target: self, action: "panning:");
                }
}

.. 在 vi​​ewDidLoad 中调用函数：

    // loop from 0 to 50
    for i in 0...50 {

        // create a square object
        let square = UIView()
        square.frame = CGRect(x: 55, y: 300, width: 40, height: 40)
        square.backgroundColor = UIColor.redColor()
        self.view.addSubview(square)


        let recognizer = UIPanGestureRecognizer(target: self, action: "panning:");
        recognizer.delegate = self;
        square.addGestureRecognizer(recognizer)
        panGesture.delegate = self;

感谢 Rob 的反馈，这是一个更新版本：

我真的不知道如何将 AllowUserInteraction 添加到 CAKeyframeAnimation（Rob 的回答 3a），因为它没有“选项”字段（我是菜鸟）。

停止正在移动的对象的动画（Rob 的答案 3b）完全让我无法理解。但这里绝对有必要。

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    srand48(Int(NSDate().timeIntervalSince1970))

    // loop from 0 to 5
    for i in 0...5 {

        // create a square
        let square = UIView()
        square.frame = CGRect(x: 55, y: 300, width: 40, height: 40)
        square.backgroundColor = UIColor.redColor()

        self.view.addSubview(square)
        //square.userInteractionEnabled = true;


        let recognizer = UIPanGestureRecognizer(target: self, action: "panning:");
        square.addGestureRecognizer(recognizer)



        // randomly create a value between 0.0 and 150.0
        let randomYOffset = CGFloat( drand48() * 150)

        // for every y-value on the bezier curve
        // add our random y offset so that each individual animation
        // will appear at a different y-position
        let path = UIBezierPath()
        path.moveToPoint(CGPoint(x: -16,y: 239 + randomYOffset))
        path.addCurveToPoint(CGPoint(x: 375, y: 239 + randomYOffset), controlPoint1: CGPoint(x: 136, y: 373 + randomYOffset), controlPoint2: CGPoint(x: 178, y: 110 + randomYOffset))

        // create the animation
        let anim = CAKeyframeAnimation(keyPath: "position")
        anim.path = path.CGPath
        anim.rotationMode = kCAAnimationRotateAuto
        anim.repeatCount = Float.infinity
        //anim.duration = 5.0

        // each square will take between 4.0 and 8.0 seconds
        // to complete one animation loop
        anim.duration = 4.0 + 3 * drand48()

        // stagger each animation by a random value
        // `290` was chosen simply by experimentation
        anim.timeOffset = 290 * drand48()


        // add the animation 
        square.layer.addAnimation(anim, forKey: "animate position along path")
    }
}


func panning(pan: UIPanGestureRecognizer) {

    if pan.state == .Began {
        println("pan began")
        self.view.bringSubviewToFront(pan.view!)

    } else if pan.state == .Changed {

        println("pan state changed")

        var translation  = pan.translationInView(self.view)

        pan.view?.center = CGPointMake(pan.view!.center.x + translation.x, pan.view!.center.y + translation.y)

        pan.setTranslation(CGPointZero, inView: self.view)

        println("translation")

    }
}

Answer 1

我突然想到了两件事：

1. 您的for 循环正在为recognizer（除非您正在做一些您没有与我们分享的特定事情）和panGesture（应该删除因为panGesture 是不是您在此for 循环中设置的变量，并且似乎完全不相关）。因此它将是：

   for i in 0...50 {
       let square = UIView()
       square.frame = CGRect(x: 55, y: 300, width: 40, height: 40)
       square.backgroundColor = UIColor.redColor()
       self.view.addSubview(square)
   
       let recognizer = UIPanGestureRecognizer(target: self, action: "panning:");
       square.addGestureRecognizer(recognizer)
   }
   

2. 在panning 中，您正在实例化一个新的panGesture：您肯定想摆脱它。手势处理程序没有创建新手势的业务。所以去掉以let panGesture = ...开头的那一行。

3. 在您最初的问题中，您没有分享您正在制作的动画。如果您使用基于块的动画制作动画，则必须指定 UIViewAnimationOptions.AllowUserInteraction 选项。此外，如果您开始在正在动画的视图周围拖动它，您还需要 (a) 停止该视图的动画； (b) 按照presentationLayer重置frame。

   但是，现在很明显您正在使用CAKeyframeAnimation，在这种情况下，没有AllowUserInteraction 机制。因此，您必须将手势识别器添加到superview，然后遍历正方形的帧（由它们的表示层表示，即动画中间的位置）并测试是否有任何命中.

4. 这取决于您，但我发现平移手势开始识别手势有点慢（因为它区分平移和轻敲。在这种情况下，您想要一些响应更快的东西，我想，所以我可能会使用带有

的长按手势识别器

因此，将所有这些放在一起，您最终会得到如下结果：

var squares = [UIView]() // an array to keep track of all of the squares

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    srand48(Int(NSDate().timeIntervalSince1970))

    // loop from 0 to 5
    for i in 0...5 {

        // create a square
        let square = UIView()
        square.frame = CGRect(x: 55, y: 300, width: 40, height: 40)
        square.backgroundColor = UIColor.redColor()

        self.view.addSubview(square)

        squares.append(square)

        // randomly create a value between 0.0 and 150.0
        let randomYOffset = CGFloat( drand48() * 150)

        // for every y-value on the bezier curve
        // add our random y offset so that each individual animation
        // will appear at a different y-position
        let path = UIBezierPath()
        path.moveToPoint(CGPoint(x: -16,y: 239 + randomYOffset))
        path.addCurveToPoint(CGPoint(x: 375, y: 239 + randomYOffset), controlPoint1: CGPoint(x: 136, y: 373 + randomYOffset), controlPoint2: CGPoint(x: 178, y: 110 + randomYOffset))

        // create the animation
        let anim = CAKeyframeAnimation(keyPath: "position")
        anim.path = path.CGPath
        anim.rotationMode = kCAAnimationRotateAuto
        anim.repeatCount = Float.infinity
        //anim.duration = 5.0

        // each square will take between 4.0 and 8.0 seconds
        // to complete one animation loop
        anim.duration = 4.0 + 3 * drand48()

        // stagger each animation by a random value
        // `290` was chosen simply by experimentation
        anim.timeOffset = 290 * drand48()

        // add the animation
        square.layer.addAnimation(anim, forKey: "animate position along path")
    }

    let recognizer = UILongPressGestureRecognizer(target: self, action: "handleLongPress:");
    recognizer.minimumPressDuration = 0
    view.addGestureRecognizer(recognizer)
}

var viewToDrag: UIView!          // which of the squares are we dragging
var viewToDragCenter: CGPoint!   // what was the `center` of `viewToDrag` when we started to drag it
var originalLocation: CGPoint!   // what was gesture.locationInView(gesture.view!) when we started dragging

func handleLongPress(gesture: UILongPressGestureRecognizer) {
    let location = gesture.locationInView(gesture.view!)

    if gesture.state == .Began {
        for square in squares {
            let presentationLayer = square.layer.presentationLayer() as CALayer
            let frame = presentationLayer.frame
            if CGRectContainsPoint(frame, location) {
                viewToDrag = square
                viewToDragCenter = CGPointMake(CGRectGetMidX(frame), CGRectGetMidY(frame))
                viewToDrag.layer.removeAnimationForKey("animate position along path")
                viewToDrag.center = viewToDragCenter
                originalLocation = location
                return
            }
        }
    } else if gesture.state == .Changed {
        if viewToDrag != nil {
            var translation = CGPointMake(location.x - originalLocation.x, location.y - originalLocation.y)
            viewToDrag.center = CGPointMake(viewToDragCenter.x + translation.x, viewToDragCenter.y + translation.y)
        }
    } else if gesture.state == .Ended {
        viewToDrag = nil
    }
}