平移手势无法正常工作

Question

所以我正在创建一个带有网格的应用程序，当我点击时它会创建一个节点。 现在，我目前正在使用 PanGesture 将节点拖放到网格中的不同位置。 现在，我希望我拖动的节点更大（这样用户更容易看到），然后在放下它时恢复到它的大小。 所以我使用“panGesture.state == begin”来实现一个放大节点的动画。 但是，此动画仅在节点开始移动时才开始，而不是在我触摸它时立即开始。 根据苹果 API，

A pan gesture recognizer enters the began state as soon as the 
**required amount of initial movement is achieved**

这意味着在我开始拖动节点之前，我的节点不会变大。

有什么办法可以解决这个问题吗？

Answer 1

您可以同时使用长按和平移手势识别器。 请参阅代码示例。

class ViewController: UIViewController, UIGestureRecognizerDelegate {
   var dragView: UIView!

   override func viewDidLoad() {
      super.viewDidLoad()

      self.dragView = UIView(frame: CGRect(x: 100.0, y: 100, width: 50.0, height: 50.0))
      self.dragView.backgroundColor = UIColor.red

      let panRecognizer = UIPanGestureRecognizer(target: self, action: #selector(pan))
      panRecognizer.delegate = self
      self.dragView.addGestureRecognizer(panRecognizer)

      let pressRecognizer = UILongPressGestureRecognizer(target: self, action: #selector(press))
      pressRecognizer.minimumPressDuration = 0.0 // IMPORTANT
      pressRecognizer.delegate = self
      self.dragView.addGestureRecognizer(pressRecognizer)

      self.view.addSubview(self.dragView)
   }

   @objc
   func press(gestureRecognizer: UILongPressGestureRecognizer) {
      switch gestureRecognizer.state {
         case .began:
            UIView.animate(withDuration: 0.1, animations: {
               self.dragView.transform = CGAffineTransform(scaleX: 1.1, y: 1.1)
            })
         case .cancelled, .ended, .failed:
            UIView.animate(withDuration: 0.1, animations: {
               self.dragView.transform = CGAffineTransform.identity
            })
         default: break
      }
   }

   @objc
   func pan(gestureRecognizer: UIPanGestureRecognizer) {
      switch gestureRecognizer.state {
         case .changed:
            var center = self.dragView.center
            let translation = gestureRecognizer.translation(in: self.dragView)
            center.x += translation.x
            center.y += translation.y
            self.dragView.center = center
            gestureRecognizer.setTranslation(CGPoint.zero, in: self.dragView)
         default: break
      }
   }

   // MARK: UIGestureRecognizerDelegate
   @objc
   func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer,
                          shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
      return true // IMPORTANT
   }
}

Answer 2

在平移手势中，.began 表示开始移动而不是开始触摸。 您必须覆盖 func touchesBegan(_ touches: Set, with event: UIEvent?) 函数才能获得实际触摸。