21. 手势识别之UITapGestureRecognizer

UITapGestureRecognizer

点击手势, 可以设置单击,双击,多击,还可以设置使用几根手指, 下面我们学习如何使用它

1.UITapGestureRecognizer的创建

import UIKitclass ViewController: UIViewController {    var label: UILabel?    override func viewDidLoad() {        super.viewDidLoad()        label = UILabel(frame: CGRect(x: 20, y: 20, width: 300, height: 60))        label?.textAlignment = .Center        self.view.addSubview(label!)        let tap = UITapGestureRecognizer(target: self, action: "tapAction:")        // 需要点击的次数        tap.numberOfTapsRequired = 2        // 需要触摸的手指数        tap.numberOfTouchesRequired = 2        self.view.addGestureRecognizer(tap)    }    override func didReceiveMemoryWarning() {        super.didReceiveMemoryWarning()        // Dispose of any resources that can be recreated.    }    func tapAction(tapGestureRecognizer: UITapGestureRecognizer) {        self.label?.text = "点击手势"    }}

运行程序

2. UITapGestureRecognizer详解

我们查看UITapGestureRecognizer的定义:

@available(iOS 3.2, *)public class UITapGestureRecognizer : UIGestureRecognizer {    // 需要点击的数目, 默认值是1    public var numberOfTapsRequired: Int     // 指定手指数, 默认值是1    public var numberOfTouchesRequired: Int }

这个类的属性还是蛮少的

3. UITapGestureRecognizer的坑

默认情况下,如果同时设置了单击和双击, 那么双击时,单击也会触发,要解决这个问题,我们要使用requireGestureRecognizerToFail方法, 它是UIGestureRecognizer的方法. 代码在第四部分中展示

4. 完整代码

import UIKitclass ViewController: UIViewController {    var label: UILabel?    override func viewDidLoad() {        super.viewDidLoad()        label = UILabel(frame: CGRect(x: 20, y: 20, width: 300, height: 60))        label?.textAlignment = .Center        self.view.addSubview(label!)        let tap = UITapGestureRecognizer(target: self, action: "tapAction:")        // 需要点击的次数        tap.numberOfTapsRequired = 2        // 需要触摸的手指数        tap.numberOfTouchesRequired = 2        self.view.addGestureRecognizer(tap)        let tapSingle = UITapGestureRecognizer(target: self, action: "tapAction2:")        // 需要点击的次数        tapSingle.numberOfTapsRequired = 1        // 需要触摸的手指数        tapSingle.numberOfTouchesRequired = 2        tapSingle.requireGestureRecognizerToFail(tap)        self.view.addGestureRecognizer(tapSingle)    }    override func didReceiveMemoryWarning() {        super.didReceiveMemoryWarning()        // Dispose of any resources that can be recreated.    }    func tapAction(tapGestureRecognizer: UITapGestureRecognizer) {        self.label?.text = "点击手势"        print("双击")    }    func tapAction2(tapGestureRecognizer: UITapGestureRecognizer) {        print("单击")    }}