UIPanGestureRecognizer不工作

Question

这很奇怪，但是当我向视图中添加一个UIPanGestureRecognizer时，它就不能工作了。我认为，白色视图是红色视图的一个子视图：

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主视图：

@IBOutlet weak var redView: UIView!
@IBOutlet weak var whiteView: UIView!
override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    let panRecognizer = UIPanGestureRecognizer(target:self, action:#selector(ViewController.handlePan))
    whiteView.gestureRecognizers = [panRecognizer]        
}


func handlePan(recognizer:UIPanGestureRecognizer)  {
    //foo
}

当我点击并拖动白色视图时，它不会移动。

Answer 1

以下是答案：

class ViewController: UIViewController {

    @IBOutlet weak var redView: UIView!
    @IBOutlet weak var whiteView: UIView!

    var lastLocation:CGPoint = CGPointMake(0, 0)


    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        let panRecognizer = UIPanGestureRecognizer(target:self, action:#selector(ViewController.handlePan))
        whiteView.addGestureRecognizer(panRecognizer)

    }


    func handlePan(recognizer:UIPanGestureRecognizer)  {
        let translation  = recognizer.translationInView(redView)
        whiteView.center = CGPointMake(lastLocation.x + translation.x, lastLocation.y + translation.y)
    }

    override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
        // Promote the touched view
        lastLocation = whiteView.center

    }
}

Answer 2

试试这个：

whiteView.isUserInteractionEnabled = true

Answer 3

来自苹果公司的文档：

如果pan手势识别器的代码未被称为，请检查以下条件是否为真，并根据需要进行更正：

视图的isUserInteractionEnabled属性设置为真。默认情况下，图像视图和标签将此属性设置为false。

minimumNumberOfTouches属性中指定的值与maximumNumberOfTouches属性中指定的值之间有接触的数。

对于UIScreenEdgePanGestureRecognizer对象，边缘属性被配置，并从适当的边缘开始。

处理潘手势