想让图像只向上平移。
我试图编辑x和y坐标。试图根据翻译创建一个新的y变量,但不会改变。
@objc func handleVerticalPan(_ recognizer: UIPanGestureRecognizer) {
let translation: CGPoint = recognizer.translation(in: self.view)
var newY = view.center.y + translation.y
startingPoint = recognizer.view!.center
recognizer.view?.superview?.bringSubviewToFront(recognizer.view!)
if newY > translation.y
{
recognizer.view?.center = CGPoint(x: recognizer.view!.center.x, y: recognizer.view!.center.y + translation.y)
newY = view.center.y + translation.y
recognizer.setTranslation(CGPoint(x: 0, y: 0), in: self.view)
//startingPoint = recognizer.view!.center
}
它会上下颠簸,但我只想让它上升。
您正在比较错误的变量,并且Y
值在向下方向上增加。你需要检查的是transition.y
是否定的(即向上移动):
替换这个:
if newY > translation.y
有了这个:
if transition.y < 0
事实上,newY
根本不需要:
@objc func handleVerticalPan(_ recognizer: UIPanGestureRecognizer) {
let translation = recognizer.translation(in: self.view)
guard let view = recognizer.view else { return }
view.superview?.bringSubviewToFront(view)
// If the movement is upward (-Y direction):
if translation.y < 0
{
view.center = CGPoint(x: view.center.x, y: view.center.y + translation.y)
recognizer.setTranslation(.zero, in: self.view)
}
}
笔记:
其他变化:
guard
安全地解开recognizer.view
一次,而不是在整个代码中重复展开它。CGPoint(x: 0, y: 0)
替换为.zero
,其中Swift推断为CGPoint.zero
,因为它期待一个CGPoint
。