（Target-Action,协议，闭包）
简单控件用闭包
复杂控件用协议
新建一个类ProtocolSlider
//协议的优点：明确
//协议的缺点：复杂，步骤太多
//如果有optional方法，必须使用@objc
@objc protocol ProtocolSliderDelegate {
optional func didChange(slider: ProtocolSlider类名)
}
class ProtocolSlider: UIView {
let trackView = UIView()
// 用于关联两个对象(控件与需要获取事件的对象)
var delegate: ProtocolSliderDelegate!
// 如果使用闭包，定义一个闭包
// var didChange: ((ProtocolSlider) -> Void)!
var minValue: CGFloat = 0
var maxValue: CGFloat = 1
var currentValue: CGFloat = 0.5 {
didSet {
// self.sendActionsForControlEvents(.ValueChanged)
self.setNeedsLayout()
}
}
override init(frame: CGRect) {
super.init(frame: frame)
self.addSubview(trackView)
self.backgroundColor = UIColor.cyanColor()
trackView.backgroundColor = UIColor.redColor()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
self.addSubview(trackView)
self.backgroundColor = UIColor.cyanColor()
trackView.backgroundColor = UIColor.redColor()
}
func moveTrack(touches: NSSet) {
let touch = touches.anyObject() as! UITouch
let location = touch.locationInView(self)
currentValue = (location.x / self.frame.size.width) * (maxValue - minValue) +minValue
}
//开始触摸
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
// print("begin")
moveTrack(touches)
}
//移动
override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) {
// print("continue")
moveTrack(touches)
}
override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) {
// print("end")
//触发事件
// self.sendActionsForControlEvents(.ValueChanged)
// 实现闭包
// 1. 如果使用协议，需要确保delegate是否为空
// 2. 如果方法为optional，需要确保方法是否实现
// if delegate != nil {
// if delegate.didChange != nil {
// delegate.didChange!(self)
// }
// }
if didChange != nil {
didChange(self)
}
}
override func layoutSubviews() {
super.layoutSubviews()
let width = (currentValue - minValue) * self.frame.size.width / (maxValue -minValue)
let rect = CGRect(x: 0, y: 0, width: width, height: self.frame.size.height)
trackView.frame = rect
}
}
在ViewControl中实现协议
import UIKit
class ViewController: UIViewController, ProtocolSliderDelegate, UITableViewDelegate {
override func viewDidLoad() {
super.viewDidLoad()
//UIControl
//Target-Action
let slider = ProtocolSlider(frame: CGRect(x: 100, y: 100, width: 200, height:50))
// UIControl addTarget 实现方法
// slider.addTarget(self, action: #selector(didChange(_:)), forControlEvents: .ValueChanged)
// slider.delegate = self
// 调用闭包
// slider.didChange = {
// sender in
// print(sender.currentValue)
// }
//函数：特殊闭包
//闭包：匿名函数
slider.didChange = didChange 协议实现方法
self.view.addSubview(slider) 协议实现方法
}
func didChange(sender: ProtocolSlider) {
print(sender.currentValue)
}
}
