1，创建进度条

let progressView = UIProgressView(progressViewStyle: .default)
progressView.center = self.view.center
progressView.progress = 0.5 //默认进度50%
self.view.addSubview(progressView)

2，设置进度，同时有动画效果

progressView.setProgress(0.8, animated:true)

3，改变进度条颜色

progressView.progressTintColor = UIColor.green  //已有进度颜色
progressView.trackTintColor = UIColor.blue  //剩余进度颜色（即进度槽颜色）