UIProgressView和UISlider

UIProgressView和UISlider两个控件长的很像，区别在于UISlider有一个可以改变进度的滑块。虽然样子差不多，提供的属性的功能也差不多，但是属性的名字差别比较大。

- (void) createUI {
    self.progressView = [[UIProgressView alloc] initWithFrame:CGRectMake(10, 100, 200, 50)];

    self.progressView.progress = 0.5;

    self.progressView.trackTintColor = [UIColor grayColor];
    self.progressView.progressTintColor = [UIColor redColor];

    [self.view addSubview:self.progressView];

    self.slider = [[UISlider alloc] initWithFrame:CGRectMake(10, 160, 200, 50)];
    self.slider.value = 50;
    self.slider.maximumValue = 100;
    self.slider.minimumValue = 0;
    self.slider.maximumTrackTintColor = [UIColor grayColor];
    self.slider.minimumTrackTintColor = [UIColor redColor];

    [self.view addSubview:self.slider];
    [self.slider addTarget:self action:@selector(updateProgress) forControlEvents:UIControlEventValueChanged];
}

ps：UISlider可以通过UIControlEventValueChanged监听进度的变化，UIProgressView不能监听进度的变化。