class ProgressView: UIView {    // MARK:- 定义属性    var progress : CGFloat = 0 {        didSet {            setNeedsDisplay()        }    }        // MARK:- 重写drawRect方法    override func drawRect(rect: CGRect) {        super.drawRect(rect)        // 获取参数        let center = CGPoint(x: rect.width * 0.5, y: rect.height * 0.5)        let radius = rect.width * 0.5 - 3        let startAngle = CGFloat(-M_PI_2)        let endAngle = CGFloat(2 * M_PI) * progress + startAngle                // 创建贝塞尔曲线        let path = UIBezierPath(arcCenter: center, radius: radius, startAngle: startAngle, endAngle: endAngle, clockwise: true)                // 绘制一条中心点的线        path.addLineToPoint(center)        path.closePath()                // 设置绘制的颜色        UIColor(white: 1.0, alpha: 0.4).setFill()                // 开始绘制        path.fill()    }}

progressView.bounds = CGRect(x: 0, y: 0, width: 50, height: 50)        progressView.center = CGPoint(x: UIScreen.mainScreen().bounds.width * 0.5, y: UIScreen.mainScreen().bounds.height * 0.5)                // 3.设置控件的属性        progressView.hidden = true        progressView.backgroundColor = UIColor.clearColor()

// 4.设置imagView的图片        progressView.hidden = false        imageView.sd_setImageWithURL(getBigURL(picURL), placeholderImage: image, options: [], progress: { (current, total) -> Void in            self.progressView.progress = CGFloat(current) / CGFloat(total)            }) { (_, _, _, _) -> Void in                self.progressView.hidden = true        }