Ios 如何为自定义手势识别器实现VelocityView?
我正在实现一个自定义的Ios 如何为自定义手势识别器实现VelocityView?,ios,objective-c,uigesturerecognizer,subclass,Ios,Objective C,Uigesturerecognizer,Subclass,我正在实现一个自定义的uigesturecognizer子类 我想实现VelocityView:与UIPangestureRecognitizer的实现方式相同。但我不知道该怎么做。如何以点/秒为单位计算速度?首先,如果使用Swift,则需要创建桥接标头并导入,以便覆盖UIGestureRegoniser的触摸开始/移动/取消/结束方法。如果您使用的是Objective-C,只需将import语句放在.h或.m文件中即可 其次,一旦创建了UIgestureRecognitor子类,您需要在其中包
uigesturecognizer
子类
我想实现
VelocityView:
与UIPangestureRecognitizer
的实现方式相同。但我不知道该怎么做。如何以点/秒为单位计算速度?首先,如果使用Swift,则需要创建桥接标头并导入,以便覆盖UIGestureRegoniser
的触摸开始/移动/取消/结束方法。如果您使用的是Objective-C,只需将import
语句放在.h或.m文件中即可
其次,一旦创建了UIgestureRecognitor
子类,您需要在其中包含以下变量:
private lazy var displayLink: CADisplayLink = {
let link = CADisplayLink(target: self, selector: Selector("timerCalled"))
link.addToRunLoop(NSRunLoop.currentRunLoop(), forMode: NSRunLoopCommonModes)
return link
}()
private var previousTouchLocation: CGPoint?
private var currentTouchLocation : CGPoint?
private var previousTime: Double?
private var currentTime : Double?
显示链接用于更新currentTime
和previousTime
第三,要继续设置所有内容,您需要覆盖以下方法,我认为这一切都是不言自明的:
override func touchesBegan(touches: Set<NSObject>!, withEvent event: UIEvent!) {
self.state = .Began
displayLink.paused = false
}
override func touchesMoved(touches: Set<NSObject>!, withEvent event: UIEvent!) {
if let view = self.view,
touch = touches.first as? UITouch {
self.state = .Changed
let newLocation = touch.locationInView(view)
self.previousTouchLocation = self.currentTouchLocation
self.currentTouchLocation = newLocation
}
}
override func touchesEnded(touches: Set<NSObject>!, withEvent event: UIEvent!) {
self.state = .Ended
displayLink.paused = true
}
override func touchesCancelled(touches: Set<NSObject>!, withEvent event: UIEvent!) {
self.state = .Cancelled
displayLink.paused = true
}
使用以下方程式计算速度:
velocity = deltaDistance / deltaTime
在这种情况下,取速度的每个分量(x和y),并使用该方程计算每个轴上的速度。如果你想结合速度的两个分量,你可以使用毕达哥拉斯定理,如下所示:
let distance = hypot(targetCurrLocation.x - targetPrevLocation.x,
targetCurrLocation.y - targetPrevLocation.y)
let velocity = distance / deltaTime
第五,在视图控制器中,您现在可以添加手势识别器,并使用操作
在屏幕上拖动时获得速度:
override func viewDidLoad() {
super.viewDidLoad()
let recognizer = VelocityGestureRecognizer(target: self, action: Selector("movedGesture:"))
self.view.addGestureRecognizer(recognizer)
}
func movedGesture(recognizer: VelocityGestureRecognizer) {
let v = recognizer.velocityInView(self.view)
println("velocity = \(v)")
}
不用swift,但没关系,我会翻译。
override func viewDidLoad() {
super.viewDidLoad()
let recognizer = VelocityGestureRecognizer(target: self, action: Selector("movedGesture:"))
self.view.addGestureRecognizer(recognizer)
}
func movedGesture(recognizer: VelocityGestureRecognizer) {
let v = recognizer.velocityInView(self.view)
println("velocity = \(v)")
}