import UIKit

class ProgressControl: UIView {

 
 override init(frame: CGRect) {
 super.init(frame: frame)
 
 self.backgroundColor = UIColor(white: 1, alpha: 0)//初始化繪圖背景為白色；
 }
 
 required init(coder aDecoder: NSCoder) {
 super.init(coder: aDecoder)
 }

 private var _progressValue:CGFloat = 0//這個就是當前的進度；
 
 func getProgressValue()->CGFloat{
 
 return _progressValue
 }
 
 func setProgressvalue(value:CGFloat){//設(shè)置進度；
 
 _progressValue = value
 
 setNeedsDisplay()
 }

 
 override func drawRect(rect: CGRect) {//繪制圓形背景和扇形進度；
 
 var context = UIGraphicsGetCurrentContext()
 
 var r = rect.width/2
 
 CGContextAddArc(context, r, r, r, 0, 3.1415926 * 2 , 0)
 CGContextSetRGBFillColor(context, 0.5, 0.5, 0.5, 1)
 CGContextFillPath(context)
 
 CGContextAddArc(context, r, r, r, 0, 3.1415926 * 2 * _progressValue, 0)
 CGContextAddLineToPoint(context, r, r)
 CGContextSetRGBFillColor(context, 0, 0, 1, 1)
 CGContextFillPath(context)
 
 }
 
}

import UIKit

class ViewController: UIViewController {

 var progressControl:ProgressControl!
 
 override func viewDidLoad() {
 super.viewDidLoad()

 
 progressControl = ProgressControl(frame:CGRect(x: 100, y: 100, width: 100, height: 100))
 self.view.addSubview(progressControl)
 
 }
 
 //點擊按鈕，增加進度
 @IBAction func addProgressValuePressed(sender: UIButton) {
 
 progressControl.setProgressvalue(progressControl.getProgressValue()+0.1)
 
 }

 override func didReceiveMemoryWarning() {
 super.didReceiveMemoryWarning()
 // Dispose of any resources that can be recreated.
 }


}