Swift 如何实现手势识别，单点 长按 旋转 放大

此文转载自：http://www.oschina.net/translate/implement-gesture-recognizers-swift

在这次IOS应用开发教程中，我们打算实现手势识别。正如你所知道的，IOS支持大量的手势操作，它们能提供了很好的应用控制和出色用户体验。

让我们开始吧!

首先需要在Xcode中创建一个新的Single View Application:

然后点击Next，弹出的窗口要求你填写项目设置。在第一栏 (“Product name”) 中填入项目名称后，点击Next.

确保语言选择的是 “Swift”.

设计界面

点击 “Main.storyboard” 文件，拖出6个 UIViews放到视图中.把视图排列成如图所示的样子.当你排列UIViews时，在每个view下面添加一个UILabel并依图设定文本值。

我们开始写代码吧.

是时候编辑实现文件了 (在我们的案例 “ViewController.swift” ).

为了声明一些我们将会用到的变量，要在 “class ViewController: UIViewController“块中添加如下代码.

class ViewController: UIViewController {
    @IBOutlet var tapView: UIView
    @IBOutlet var swipeview: UIView
    @IBOutlet var longPressView: UIView
    @IBOutlet var pinchView: UIView
    @IBOutlet var rotateView: UIView
    @IBOutlet var panView: UIView
    var lastRotation = CGFloat()
    let tapRec = UITapGestureRecognizer()
    let pinchRec = UIPinchGestureRecognizer()
    let swipeRec = UISwipeGestureRecognizer()
    let longPressRec = UILongPressGestureRecognizer()
    let rotateRec = UIRotationGestureRecognizer()
    let panRec = UIPanGestureRecognizer()
}

在第2 – 7行，我们声明了在之前界面里排列过的 UIViews.

在第8行，我们声明了实现旋转手势要用到的变量(lastRotation).

在第 9 – 14行，我们为每个view声明了一个手势识别对象.

注意:在 Swift中，我们用let关键字声明常量，这意味着它的值在程序运行时不可改变。关键字var则声明普通变量。

override func viewDidLoad() {
    super.viewDidLoad()
    tapRec.addTarget(self,action: "tappedView")
    pinchRec.addTarget(self,action: "pinchedView:")
    swipeRec.addTarget(self,action: "swipedView")
    longPressRec.addTarget(self,action: "longpressedView")
    rotateRec.addTarget(self,action: "rotatedView:")
    panRec.addTarget(self,action: "draggedView:")
    tapView.addGestureRecognizer(tapRec)
    swipeview.addGestureRecognizer(swipeRec)
    pinchView.addGestureRecognizer(pinchRec)
    longPressView.addGestureRecognizer(longPressRec)
    rotateView.addGestureRecognizer(rotateRec)
    panView.addGestureRecognizer(panRec)
    rotateView.userInteractionEnabled = true
    rotateView.multipletouchEnabled = true
    pinchView.userInteractionEnabled = true
    pinchView.multipletouchEnabled = true
    tapView.userInteractionEnabled = true
    swipeview.userInteractionEnabled = true
    longPressView.userInteractionEnabled = true
    panView.userInteractionEnabled = true
}

第 3 – 8行，为每个视图设定手势识别的目标。所谓的目标，就是每个view中的手势完成后要调用的方法。

第 9 -14行，把手势识别添加到视图中.

第15 – 22行，把每个视图的userInteractionEnabled属性设为ture，并把拥有需要多点触控(rotateViewandpinchView)的手势所在的视图的multipletouchEnabled属性设为true.

现在，我们编写每个手势识别器要调用的方法 (第3 – 8行设置的目标方法 ).

添加如下代码:

func tappedView(){
    let tapAlert = UIAlertController(title: "Tapped",message: "You just tapped the tap view",preferredStyle: UIAlertControllerStyle.Alert)
    tapAlert.addAction(UIAlertAction(title: "OK",style: .Destructive,handler: nil))
    self.presentViewController(tapAlert,animated: true,completion: nil)
}
  
func swipedView(){
    let tapAlert = UIAlertController(title: "Swiped",message: "You just swiped the swipe view",completion: nil)
}
  
func longpressedView(){
    let tapAlert = UIAlertController(title: "Long pressed",message: "You just long pressed the long press view",completion: nil)
}

func rotatedView(sender:UIRotationGestureRecognizer){
    var lastRotation = CGFloat()
    self.view.bringSubviewToFront(rotateView)
    if(sender.state == UIGestureRecognizerState.Ended){
    lastRotation = 0.0;
    }
    rotation = 0.0 - (lastRotation - sender.rotation)
    var point = rotateRec.locationInView(rotateView)
    var currentTrans = sender.view.transform
    var newTrans = CGAffineTransformRotate(currentTrans,rotation)
    sender.view.transform = newTrans
    lastRotation = sender.rotation
}

func pinchedView(sender:UIPinchGestureRecognizer){
    self.view.bringSubviewToFront(pinchView)
    sender.view.transform = CGAffineTransformScale(sender.view.transform,sender.scale,sender.scale)
    sender.scale = 1.0
}

func draggedView(sender:UIPanGestureRecognizer){
    self.view.bringSubviewToFront(sender.view)
    var translation = sender.translationInView(self.view)
    sender.view.center = CGPointMake(sender.view.center.x + translation.x,sender.view.center.y + translation.y)
    sender.setTranslation(CGPointZero,inView: self.view)
}