效果图如下：

悬浮按钮

一个iOS上的悬浮按钮，实现方式是写一个自定义类继承自UIButton ，重写3个方法: touchesBegan, touchesMoved, touchesEnded ，项目中的需求是监听按钮的单击和双击事件。

以下给出源代码 swift3实现：

AllFloatButton.swift

import UIKit

// 声明协议
protocol FloatDelegate {
    func singleClick()
    
    func repeatClick()
}

class AllFloatButton: UIButton {
    
    // 是否可拖拽
    var isDragEnable: Bool = true
    
    // 拖拽后是否自动移到边缘
    var isAbsortEnable: Bool = true
    
    // 背景颜色
    var bgColor: UIColor? = UIColor.red
    
    // 正常情况下 透明度
    var alphaOfNormol: CGFloat = 0.2
    
    // 拖拽时的透明度
    var alphaOfDrag: CGFloat = 0.8
    
    // 圆角大小
    var radiuOfButton: CGFloat = 12
    
    // 拖拽结束后的等待时间
    var timeOfWait: CGFloat = 1.5
    
    // 拖拽结束后的过渡动画时间
    var timeOfAnimation: CGFloat = 0.3
    
    // 按钮距离边缘的内边距
    var paddingOfbutton: CGFloat = 2
    
    // 代理
    var delegate: FloatDelegate? = nil
    
    // 计时器
    fileprivate var timer: Timer? = nil
    
    // 内部使用 起到数据传递的作用
    fileprivate var allPoint: CGPoint? = nil
    
    // 内部使用
    fileprivate var isHasMove: Bool = false
    
    fileprivate var isFirstClick: Bool = true
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        self.backgroundColor = self.bgColor
        self.alpha =  self.alphaOfNormol
        self.layer.cornerRadius = self.radiuOfButton
        
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        self.alpha = self.alphaOfDrag
        // 计时器取消
        self.timer?.invalidate()
        // 不可拖拽则退出执行
        if !isDragEnable {
            return
        }
        self.allPoint = touches.first?.location(in: self)
        if touches.first?.tapCount == 1  {
            self.perform(#selector(singleClick), with: nil, afterDelay: 0.2)
        } else if touches.first?.tapCount == 2 {
            self.perform(#selector(repeatClick))
        }
    }
    
    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        self.isHasMove = true
        if self.isFirstClick {
            NSObject.cancelPreviousPerformRequests(withTarget: self, selector: #selector(singleClick), object: nil)
            self.isFirstClick = false
        }
        if !isDragEnable {
            return
        }
        let temp = touches.first?.location(in: self)
        // 计算偏移量
        let offsetx = (temp?.x)! - (self.allPoint?.x)!
        let offsety = (temp?.y)! - (self.allPoint?.y)!
        self.center = CGPoint.init(x: self.center.x + offsetx, y: self.center.y + offsety)
    }
    
    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        self.isFirstClick = true
        self.timer = Timer.init(timeInterval: TimeInterval(self.timeOfWait), repeats: false, block: { (Timer) in
            // 过渡
            UIView.animate(withDuration: TimeInterval(self.timeOfAnimation), animations: {
                self.alpha = self.alphaOfNormol
            })
        })
        // 这段代码只有在按钮移动后才需要执行
        if self.isHasMove && isAbsortEnable && self.superview != nil {
            // 移到父view边缘
            let marginL = self.frame.origin.x
            let marginT = self.frame.origin.y
            let superFrame = self.superview?.frame
            let tempy = (superFrame?.height)! - 2 * self.frame.height - self.paddingOfbutton
            let tempx = (superFrame?.width)! - self.frame.width - self.paddingOfbutton
            let xOfR = (superFrame?.width)! - self.frame.width - self.paddingOfbutton
            UIView.animate(withDuration: 0.2, animations: {
                var x = self.frame.origin.x
                if marginT < self.frame.height + self.paddingOfbutton {
                    // 靠顶部
                    if x > tempx {
                        x = tempx
                    }
                    if x < self.paddingOfbutton {
                        x = self.paddingOfbutton
                    }
                    self.frame = CGRect.init(x: x, y: self.paddingOfbutton, width: self.frame.width, height: self.frame.height)
                } else if marginT > tempy {
                    // 靠底部
                    if x > tempx {
                        x = tempx
                    }
                    if x < self.paddingOfbutton {
                        x = self.paddingOfbutton
                    }
                    let y = tempy + self.frame.height
                    self.frame = CGRect.init(x: x, y: y, width: self.frame.width, height: self.frame.height)
                } else if marginL > ((superFrame?.width)! / 2) {
                    // 靠右移动
                    self.frame = CGRect.init(x: xOfR, y: marginT, width: self.frame.width, height: self.frame.height)
                } else {
                    // 靠左移动
                    self.frame = CGRect.init(x: self.paddingOfbutton, y: marginT, width: self.frame.width, height: self.frame.height)
                }
            })
        }
        self.isHasMove = false
        // 将计时器加入runloop
        if let temptime = self.timer {
            RunLoop.current.add(temptime, forMode: .commonModes)
        }
    }
    
    func singleClick() {
        self.delegate?.singleClick()
    }
    
    func repeatClick() {
        NSObject.cancelPreviousPerformRequests(withTarget: self, selector: #selector(singleClick), object: nil)
        self.delegate?.repeatClick()
    }
}

代理对象实现协议，执行代理方法：

ViewController.swift：

import UIKit

class ViewController: UIViewController, FloatDelegate {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let frame = CGRect.init(x: 3, y: 100, width: 60, height: 60)
        let allbutton = AllFloatButton.init(frame: frame)
        allbutton.delegate = self
        self.view.addSubview(allbutton)

        let frame2 = CGRect.init(x: 3, y: 300, width: 60, height: 60)
        let allbutton2 = AllFloatButton.init(frame: frame2)
        // 拖拽后不能回到边缘
        allbutton2.isAbsortEnable = false
        allbutton2.backgroundColor = UIColor.black
        self.view.addSubview(allbutton2)
        
    }
    
    // 实现代理方法
    func singleClick() {
        print("单击")
    }
    
    func repeatClick() {
        print("双击")
    }
}