转载请声明出处：——————————————————————————————概述
——————————————————————————————代码示例import UIKitclass ViewController: UIViewController {var button: UIButton!var progressView: UIProgressView!var timer: NSTimer!var remainTime = 100override func viewDidLoad() {// 初始化按钮，开始倒计时button = UIButton.buttonWithType(.System) as UIButtonbutton.frame = CGRectMake(self.view.frame.width/2 – 50, 50, 100, 50)button.setTitle("开始", forState: UIControlState.Normal)button.addTarget(self, action: "buttonAction", forControlEvents: UIControlEvents.TouchUpInside)// 初始化 progressViewprogressView = UIProgressView(progressViewStyle: UIProgressViewStyle.Bar)progressView.frame = CGRectMake(self.view.frame.width/2 – 50, 200, 100, 100)// 设置初始值progressView.progress = 1.0// 设置进度条颜色progressView.progressTintColor = UIColor.blueColor()// 设置进度轨迹颜色progressView.trackTintColor = UIColor.greenColor()// 扩展：可以通过 progressImage、trackImage 属性自定义出个性进度条self.view.addSubview(button)self.view.addSubview(progressView)}/// 响应按钮点击事件，，开始倒计时func buttonAction() {button.enabled = falsetimer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: "timerAction", userInfo: nil, repeats:true)timer.fire()}// 每秒定时触发func timerAction() {if(remainTime < 0){//倒计时结束timer.invalidate()} else {println("\(remainTime)")remainTime = remainTime – 1let progressValue = Float(remainTime)/100progressView.setProgress(progressValue, animated:true)}}}——————————————————————————————结语GitHub 上项目地址：UIProgressViewSample
文章最后更新时间：2015年4月1日09:08:34。参考资料如下：
UIKit User Interface Catalog: Progress Views
也有伤心的，既有令人兴奋的，也有令人灰心的，
