UIView 转换后拖动行为错误

Question

我有一个自定义的DraggableView，它是UIImageView 的子类。我用相机拍照，将生成的UIImage 添加到DraggableView，然后我可以愉快地在屏幕上拖动它，如预期的那样。

现在，如果原始照片是横向拍摄的，我会使用以下方法旋转它：

if (image?.size.width > image?.size.height)
{
   self.transform = CGAffineTransformMakeRotation(CGFloat(M_PI_2))
}

当我应用此转换时，拖动行为仍然有效，但方向都错误 - 如果我向左拖动，图像会向上移动，而不是向左移动。如果我向上拖动，图像会向右移动，而不是向上移动。

我该如何解决这个问题？我想这与UIPanGestureRecognizer 绑定到未转换的视图有关？

编辑：当前UIPanGestureRecognizer处理程序：

func onPhotoDrag(recognizer: UIPanGestureRecognizer?)
{
    let translation = recognizer!.translationInView(recognizer?.view)
    recognizer!.view!.center = CGPointMake(recognizer!.view!.center.x 
            + translation.x, recognizer!.view!.center.y + translation.y);
    recognizer?.setTranslation(CGPointZero, inView: recognizer?.view)

    if (recognizer!.state == UIGestureRecognizerState.Ended)
    {
        let velocity = recognizer!.velocityInView(recognizer?.view)
        let magnitude = sqrt((velocity.x * velocity.x) 
                + (velocity.y * velocity.y))
        let slideMult = magnitude / 300;
        let slideFactor = 0.1 * slideMult;
        let finalPoint = CGPointMake(recognizer!.view!.center.x 
                + (velocity.x * slideFactor), 
                recognizer!.view!.center.y + (velocity.y * slideFactor));

        // Animate the drag, and allow the drag delegate to do its work
        DraggableView.animateWithDuration(Double(slideFactor), 
                delay: 0, options: UIViewAnimationOptions.CurveEaseOut,
                animations: { recognizer?.view?.center = finalPoint },
                completion: {(_) -> Void in self.dragDelegate?.onDragEnd(self)})
    } // if: gesture ended
}

Answer 1

更新：

感谢您发布代码。我将您的代码粘贴到我的DraggableImageView 并重现了您的问题。虽然我的版本正在处理旋转视图（没有动画），但你的版本是横向的。

不同之处在于我的代码在可拖动视图的superview 中要求translationInView。您需要在可拖动视图的superview 中询问translationInView 和velocityInView。

改变这一行：

let translation = recognizer!.translationInView(recognizer?.view)

到：

let translation = recognizer!.translationInView(recognizer?.view?.superview)

然后改变这个：

let velocity = recognizer!.velocityInView(recognizer?.view)

到：

let velocity = recognizer!.velocityInView(recognizer?.view?.superview)

大家都会很开心。

---

上一个答案：

试试这个版本：

class DraggableImageView: UIImageView {
    
    override var image: UIImage? {
        didSet {
            if (image?.size.width > image?.size.height)
            {
                self.transform = CGAffineTransformMakeRotation(CGFloat(M_PI_2))
            }
        }
    }

    override init(frame: CGRect) {
        super.init(frame: frame)
        
        self.setup()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        
        self.setup()
    }
    
    func setup() {
        self.userInteractionEnabled = true
        
        let panGestureRecognizer = UIPanGestureRecognizer()
        panGestureRecognizer.addTarget(self, action: #selector(draggedView(_:)))
        self.addGestureRecognizer(panGestureRecognizer)
    }
    
    func moveByDeltaX(deltaX: CGFloat, deltaY: CGFloat) {
        self.center.x += deltaX
        self.center.y += deltaY
    }
    
    func draggedView(sender:UIPanGestureRecognizer) {
        if let dragView = sender.view as? DraggableImageView, superview = dragView.superview {
            superview.bringSubviewToFront(dragView)
            let translation = sender.translationInView(superview)
            sender.setTranslation(CGPointZero, inView: superview)
            dragView.moveByDeltaX(translation.x, deltaY: translation.y)
        }
    }
}

使用示例：

override func viewDidLoad() {
    super.viewDidLoad()
    
    let dragView = DraggableImageView(frame: CGRect(x: 50, y: 50, width: 96, height: 128))
    
    dragView.image = UIImage(named: "landscapeImage.png")
    
    self.view.addSubview(dragView)
}