//
//  progressView.swift
//  swift-AFNetworking
//
//  Created by HMC on 16/8/11.
//  Copyright © 2016年 SKing. All rights reserved.
//

import UIKit

class progressView: UIView {
    
    var progress : CGFloat = 0.0  {
        //属性改变监听
        didSet {
            print("改变了")
            setNeedsDisplay()
            
        }
    }
    
    override func drawRect(rect: CGRect) {
        super.drawRect(rect)
        
        backgroundColor = UIColor.clearColor()
        let arcCenter = 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(M_PI * 2) * progress + startAngle
        
        
        let bezierPath = UIBezierPath(arcCenter: arcCenter, radius: radius, startAngle: startAngle, endAngle: endAngle, clockwise: true)
        
        bezierPath.addLineToPoint(arcCenter)
        bezierPath.closePath()
        
        UIColor(white: 1.0, alpha: 0.8).setFill()
        bezierPath.fill()
        
    }

}

控件的设置,调用方法如下,点击加载按钮 下载图片显示进度.

效果图

//
//  ViewController.swift
//  swift-AFNetworking
//
//  Created by HMC on 16/8/9.
//  Copyright © 2016年 SKing. All rights reserved.
//

import UIKit
import HYLabel
import SDWebImage

class ViewController: UIViewController {
    
    @IBAction func GoToAuth(sender: AnyObject) {
        
        let authNav = UINavigationController(rootViewController: AuthViewController())
        presentViewController(authNav, animated: true, completion: nil)
        
    }
    @IBOutlet weak var imageView: UIImageView!
    @IBAction func loadView(sender: AnyObject) {
        
        imageView.sd_setImageWithURL(NSURL(string:"http://httpbin.org/image/jpeg"), placeholderImage: nil, options: [], progress: { (current, total) in
            
            self.progress.hidden = false
            self.progress.progress = CGFloat(current) / CGFloat(total)
            
        }) { (_, _, _, _) in
            
            self.progress.hidden = true
        }
        
        SDImageCache.sharedImageCache().clearDisk()
    }
    
    //懒加载
    lazy var progress : progressView = progressView()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = UIColor.greenColor()
        view.addSubview(progress)
        progress.bounds = CGRect(x: 0, y: 0, width: 50, height: 50)
        progress.center = CGPoint(x: SCREENWIDTH * 0.5, y: SCREENHEIGHT * 0.5)
        progress.hidden = true
    }
   
    
}