21. 手势识别之UITapGestureRecognizer

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#点击手势 #手势识别 #iOS开发 #swift

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本文详细介绍了iOS开发中的点击手势识别器UITapGestureRecognizer，包括其创建、详细属性解析以及在实际使用中可能遇到的问题，如单击和双击同时触发的解决方法，并提供了完整示例代码。

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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 UIKit

class 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 UIKit

class 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")
    }
}