January 2020
Intermediate to advanced
356 pages
6h 4m
Chinese
Content preview from Swift游戏开发经典实例
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92
｜
第
3
章
dragGesture.setTranslation(CGPoint.zero,
in: dragGesture.view)
}
}
每次方法调用后，我们都需要手动将
translation
重置为
0
，因为在手势识别器下次
调用时，我们移动视图时都会从当前位置开始，而不是从拖拽一开始时候的位置开
始。
3.4
识别旋转手势
问题
如何将用户两根手指在屏幕上转动的行为识别为旋转手势？
解决方案
可以使用
UIRotationGestureRecognizer
：
class ViewController: UIViewController {
@IBOutlet weak var rotationView: UIView!
@IBOutlet weak var rotationStatusLabel: UILabel!
//
旋转的角度，以弧度为单位
var angle : Float = 0.0
//
将
self.angle
转变为度
,
//
然后用
360
度来整除
var angleDegrees : Float {
get {
return (self.angle * 180.0 / .pi)
.truncatingRemainder(dividingBy: 360)
}
}
override func viewDidLoad() {
super.viewDidLoad()
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