我创建了5个UIViews，每个都有UIPanGestureRecognizers，然后我将其添加到另一个UIView中。这一切都有效，我可以拖动每个，但我不希望它们被拖到父UIView的边界之外。我已经读过我可以使用gestureRecognizerShouldBegin函数实现UIGestureRecognizerDelegate来实现这一点，但是我找不到足够的文档来确切地知道如何实现我所需要的。像往常一样，Apple关于此的文档非常模糊。我的代码是：
let foreheadTopViewWidth = foreheadTopView.frame.width
let foreheadTopViewHeight = foreheadTopView.frame.height
let touchPointOffset = touchPointSize / 2
let touchPointYPos = (foreheadTopViewHeight / 2) - touchPointOffset
let touchPointForehead1 = TouchPoint(touchPointSize: touchPointSize, xPosition: 0, yPosition: touchPointYPos, treatmentArea: .upperForehead)
let touchPointForehead2 = TouchPoint(touchPointSize: touchPointSize, xPosition: ((foreheadTopViewWidth * 0.50) - touchPointOffset) / 2, yPosition: touchPointYPos, treatmentArea: .upperForehead)
let touchPointForehead3 = TouchPoint(touchPointSize: touchPointSize, xPosition: (foreheadTopViewWidth * 0.50) - touchPointOffset, yPosition: touchPointYPos, treatmentArea: .upperForehead)
let touchPointForehead4 = TouchPoint(touchPointSize: touchPointSize, xPosition: (foreheadTopViewWidth * 0.75) - (touchPointOffset / 0.75), yPosition: touchPointYPos, treatmentArea: .upperForehead)
let touchPointForehead5 = TouchPoint(touchPointSize: touchPointSize, xPosition: foreheadTopViewWidth - touchPointSize, yPosition: touchPointYPos, treatmentArea: .upperForehead)
foreheadTopView.addSubview(touchPointForehead1)
foreheadTopView.addSubview(touchPointForehead2)
foreheadTopView.addSubview(touchPointForehead3)
foreheadTopView.addSubview(touchPointForehead4)
foreheadTopView.addSubview(touchPointForehead5)
let foreheadGesture1 = UIPanGestureRecognizer(target: self, action: #selector(didPan(gesture:)))
let foreheadGesture2 = UIPanGestureRecognizer(target: self, action: #selector(didPan(gesture:)))
let foreheadGesture3 = UIPanGestureRecognizer(target: self, action: #selector(didPan(gesture:)))
let foreheadGesture4 = UIPanGestureRecognizer(target: self, action: #selector(didPan(gesture:)))
let foreheadGesture5 = UIPanGestureRecognizer(target: self, action: #selector(didPan(gesture:)))
foreheadGesture1.delegate = self
foreheadGesture2.delegate = self
foreheadGesture3.delegate = self
foreheadGesture4.delegate = self
foreheadGesture5.delegate = self
touchPointForehead1.addGestureRecognizer(foreheadGesture1)
touchPointForehead2.addGestureRecognizer(foreheadGesture2)
touchPointForehead3.addGestureRecognizer(foreheadGesture3)
touchPointForehead4.addGestureRecognizer(foreheadGesture4)
touchPointForehead5.addGestureRecognizer(foreheadGesture5)
foreheadTopView.layer.addSublayer(touchPointForehead1.lineTo(touchpoint: touchPointForehead2))
foreheadTopView.layer.addSublayer(touchPointForehead2.lineTo(touchpoint: touchPointForehead3))
foreheadTopView.layer.addSublayer(touchPointForehead3.lineTo(touchpoint: touchPointForehead4))
foreheadTopView.layer.addSublayer(touchPointForehead4.lineTo(touchpoint: touchPointForehead5))
@objc func didPan(gesture: UIPanGestureRecognizer) {
guard let touchpoint = gesture.view as? TouchPoint else {
return
}
if (gesture.state == .began) {
touchpoint.center = gesture.location(in: foreheadTopView)
}
let newCenter: CGPoint = gesture.location(in: foreheadTopView)
let dX = newCenter.x - touchpoint.center.x
let dY = newCenter.y - touchpoint.center.y
touchpoint.center = CGPoint(x: touchpoint.center.x + dX, y: touchpoint.center.y + dY)
if let outGoingTouchPoint = touchpoint.outGoingTouchPoint, let line = touchpoint.outGoingLine, let path = touchpoint.outGoingLine?.path {
let newPath = UIBezierPath(cgPath: path)
newPath.removeAllPoints()
newPath.move(to: touchpoint.center)
newPath.addLine(to: outGoingTouchPoint.center)
line.path = newPath.cgPath
}
if let inComingTouchPoint = touchpoint.inComingTouchPoint, let line = touchpoint.inComingLine, let path = touchpoint.inComingLine?.path {
let newPath = UIBezierPath(cgPath: path)
newPath.removeAllPoints()
newPath.move(to: inComingTouchPoint.center)
newPath.addLine(to: touchpoint.center)
line.path = newPath.cgPath
}
}
上面的代码在平移/拖动方面我需要它做的很好。我还扩展了我的ViewController以符合UIGestureRecognizerDelegate
extension ViewController: UIGestureRecognizerDelegate {
func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
}
}
但我不确定从这里开始如何限制其父视图边界内的可拖动视图。有人可以帮忙吗？
不，代表不适合这件事。我相信你想要保持手势，只是将你的观点的位置限制在他们的父母内部。为此，您需要限制平移手势更改事件。
最简单的方法是检查两个相对的点是否在父矩形内：
let topLeft = CGPoint(x: touchpoint.frame.minX + dX, y: touchpoint.frame.minY + dY)
let bottomRight = CGPoint(x: touchpoint.frame.maxX + dX, y: touchpoint.frame.maxY + dY)
if let containerView = touchpoint.superview, containerView.bounds.contains(topLeft), containerView.bounds.contains(bottomRight) {
touchpoint.center = CGPoint(x: touchpoint.center.x + dX, y: touchpoint.center.y + dY)
}
所以基本上我们正在计算新的左上角和右下角。如果这些在他们的超视图范围内，那么视图可能会移动到那一点。
这是非常好的，但事情是，一旦发生这种情况，您的视图可能不完全在边界。例如，如果用户将其向左拖动很快，那么在某些时候topLeft可能是(15, 0)，并且在下一个事件中(-10, 0)这意味着它将忽略第二个并保持在(15, 0)。
因此，您需要实现移动限制并将其限制为...
var targetFrame = CGRect(x: touchpoint.frame.origin.x + dX, y: touchpoint.frame.origin.y + dY, width: touchpoint.frame.width, height: touchpoint.frame.height)
if let containerView = touchpoint.superview {
targetFrame.origin.x = max(0.0, targetFrame.origin.x)
targetFrame.origin.y = max(0.0, targetFrame.origin.y)
targetFrame.size.width = min(targetFrame.size.width, containerView.bounds.width-(targetFrame.origin.x+targetFrame.width))
targetFrame.size.height = min(targetFrame.size.height, containerView.bounds.height-(targetFrame.origin.y+targetFrame.height))
}
touchpoint.frame = targetFrame
所以这应该让你的视图坚持在superview ...
你必须做一些计算，我希望这段代码可以帮助你。
@objc func handlepan(_ gesture:UIPanGestureRecognizer)
{
let translation = gesture.translation(in: self.imagelayer)
if let view1 = gesture.view {
if (view1.frame.origin.x + translation.x >= 0) && (view1.frame.origin.y + translation.y >= 0) && (view1.frame.origin.x + translation.x <= view1.frame.width ) && (view1.frame.origin.y + translation.y <= view1.frame.height)
{
view1.center = CGPoint(x:view1.center.x + translation.x,
y:view1.center.y + translation.y)
}
}
gesture.setTranslation(CGPoint.zero, in: self.imagelayer)
}