UIProgressView 继承自UIView,用来显示进度的,如音乐,视频的缓冲进度,文件的上传下载进度等.让用户知道当前操作完成了多少,离操作结束还有多远

AppDelegate.m

ProgressViewController *progressVC = [[ProgressViewController alloc]init];    self.window.rootViewController = progressVC;    [progressVC release];

ProgressViewController.m

@interface ProgressViewController ()@property (nonatomic,retain) UIProgressView *progressView;@property (nonatomic,retain) UILabel *label;@property (nonatomic,retain) NSTimer *timer;@end@implementation ProgressViewController- (void)dealloc{    self.progressView = nil;    self.label = nil;    self.timer = nil;    [super dealloc];}

- (void)viewDidLoad {    [super viewDidLoad];    self.view.backgroundColor = [UIColor brownColor];         //UIProgressView 继承自UIView,用来显示进度的,如音乐,视频的缓冲进度,文件的上传下载进度等.让用户知道当前操作完成了多少,离操作结束还有多远        //1.创建一个progress对象,有自己的初始化方法,创建的同时指定progress的样式,是个枚举,系统提供了2种样式    self.progressView = [[UIProgressView alloc]initWithProgressViewStyle:(UIProgressViewStyleDefault)];        //设置progress的frame,不用设置高度,设置的高度对进度条的高度没影响    _progressView.frame = CGRectMake(20, 150, 280, 0);        //2.配置属性    //2.1 设置当前进度值,范围在0.0~1.0,不可以修改最大值和最小值,默认值是0.0//    _progressView.progress = 0.5;        //2.2 设置轨道(未走过进度)的颜色    _progressView.trackTintColor = [UIColor whiteColor];        //2.3 设置进度条(已走过进度)的颜色    _progressView.progressTintColor = [UIColor redColor];        //3.添加到self.view    [self.view addSubview:self.progressView];        //4.释放    [self.progressView release];                //创建一个定时器    self.timer = [NSTimer scheduledTimerWithTimeInterval:0.05 target:self selector:@selector(progressChanged) userInfo:nil repeats:YES];        //调用label布局    [self layoutLable];}

布局label：

- (void)layoutLable{    self.label = [[UILabel alloc]initWithFrame:(CGRectMake(120, 200, 80, 40))];    _label.backgroundColor = [UIColor greenColor];    _label.font = [UIFont systemFontOfSize:22];    [self.view addSubview:self.label];}

实现定时器的方法：

- (void)progressChanged{    if (_progressView.progress >= 1.0) {        [self.timer invalidate];    }    _progressView.progress += 0.01;        //找一个float类型的变量接受当前progress的数值    float progress = self.progressView.progress * 100;    //使用接受的数值初始化一个字符串,用于label的显示    NSString *string = [NSString stringWithFormat:@"%.1f%%",progress];    _label.text = string;    self.label.textAlignment = NSTextAlignmentCenter;}