swift实现自定义圆环进度提示效果

/// ViewController.swift// PureSwiftAuto//// Created by 王木木 on 16/5/17.// Copyright © 2016年 王木木. All rights reserved.// import UIKit class ViewController: UIViewController {     let cireView = cireview.newAutoLayoutView()     override func viewDidLoad() {    super.viewDidLoad()    // Do any additional setup after loading the view, typically from a nib.    creatCire()  }     func creatCire(){    self.view.addSubview(cireView)    self.cireView.value = 2    self.cireView.maximumValue = 100    self.cireView.backgroundColor = UIColor.yellowColor()    self.cireView.frame = CGRectMake(100, 100, 100, 100)    wangmumu()  }     func wangmumu(){         self.cireView.value += 2         if self.cireView.value == 90 {return}         self.performSelector("wangmumu", withObject: self, afterDelay: 0.2)       }   }  class cireview: UIView{     var value: CGFloat = 0 {    didSet {      self.setNeedsDisplay()    }  }     var maximumValue: CGFloat = 0 {    didSet { self.setNeedsDisplay() }  }  override init(frame: CGRect) {    super.init(frame: frame)    self.opaque = false  }        override func drawRect(rect: CGRect) {    super.drawRect(rect)         //线宽度    let lineWidth: CGFloat = 10.0    //半径    let radius = CGRectGetWidth(rect) / 2.0 - lineWidth    //中心点x    let centerX = CGRectGetMidX(rect)    //中心点y    let centerY = CGRectGetMidY(rect)    //弧度起点    let startAngle = CGFloat(-90 * M_PI / 180)    //弧度终点    let endAngle = CGFloat(((self.value / self.maximumValue) * 360 - 90) ) * CGFloat(M_PI) / 180         //创建一个画布    let context = UIGraphicsGetCurrentContext()         //画笔颜色    CGContextSetStrokeColorWithColor(context, UIColor.blueColor().CGColor)         //画笔宽度    CGContextSetLineWidth(context, lineWidth)         //（1）画布 （2）中心点x（3）中心点y（4）圆弧起点（5）圆弧结束点（6） 0顺时针 1逆时针    CGContextAddArc(context, centerX, centerY, radius, startAngle, endAngle, 0)         //绘制路径    CGContextStrokePath(context)         //画笔颜色    CGContextSetStrokeColorWithColor(context, UIColor.darkGrayColor().CGColor)         //（1）画布 （2）中心点x（3）中心点y（4）圆弧起点（5）圆弧结束点（6） 0顺时针 1逆时针    CGContextAddArc(context, centerX, centerY, radius, startAngle, endAngle, 1)         //绘制路径    CGContextStrokePath(context)       }     required init?(coder aDecoder: NSCoder) {    fatalError("init(coder:) has not been implemented")  }   }