iOS进度条演示

功能展示

1. 点击“加载”按钮，启动进度条，显示“刷新”图标
2. 点击“停止”按钮，停止进度条的加载，隐藏“刷新”图标

step1-添加属性

因为要定时更新进度条，所以需要添加一个定时器对象 timer
同时，也需要保存下当前的进度， count

@interface UIDemoViewController ()

@property (nonatomic, strong) NSTimer * timer;

@property NSUInteger count;

@end 

step2-创建控件

    self.count = 0;

• 创建进度条

    // 创建进度条
    UIProgressView * prog = [[UIProgressView alloc] initWithFrame:frame];

    prog.tag = 100;
//    prog.progressViewStyle = UIProgressViewStyleBar;

    [self.view addSubview:prog];

• 创建更新图标

    UIActivityIndicatorView * aiv = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite];

    aiv.tag = 101;
    aiv.color = [UIColor blueColor];
    aiv.frame = CGRectMake(220, 65, 30, 30);


    [self.view addSubview:aiv];

• 创建定时器

    [self.timer setFireDate:[NSDate distantFuture]];
    [self.timer fire];

• 创建启动、停止按钮

    UIButton * start = [UIButton buttonWithType:UIButtonTypeSystem];
    start.frame = CGRectMake(50, 100, 50, 44);
    [start setTitle:@"加载" forState:UIControlStateNormal];
    [start addTarget:self action:@selector(startLoad) forControlEvents:UIControlEventTouchUpInside];

    [self.view addSubview:start];

    // 创建停止按钮
    UIButton * stop = [UIButton buttonWithType:UIButtonTypeSystem];
    stop.frame = CGRectOffset(start.frame, 80, 0);
    [stop setTitle:@"停止" forState:UIControlStateNormal];
    [stop addTarget:self action:@selector(stopLoad) forControlEvents:UIControlEventTouchUpInside];

    [self.view addSubview:stop];

step3-事件响应

    [self.timer setFireDate:[NSDate distantPast]];

    // 重新复位进度
    self.count = 0;

    // 显示加载动画
    UIActivityIndicatorView * aiv = (UIActivityIndicatorView *)[self.view viewWithTag:101];

    [aiv startAnimating];

}


- (void) stopLoad {

    [self.timer setFireDate:[NSDate distantFuture]];

    UIActivityIndicatorView * aiv = (UIActivityIndicatorView *)[self.view viewWithTag:101];

    [aiv stopAnimating];
}


- (void) refresh {

    UIProgressView * prog = (UIProgressView *)[self.view viewWithTag:100];

    prog.progress = (self.count++) / 100.0;

    NSLog(@"progress: %lf", prog.progress);

    if (self.count >= 100) {
        [self stopLoad];
    }

}

注意

1. 定时器的“停止”是 [self.timer setFireDate:[NSDate distantFuture]]; 代表设置，定时器的触发时间在未来，所以，肯定不会被触发。
2. 将代表进度值的设置成 属性，当需要复位进度条时，只需要将 count 清零即可。