自定义label及block动画的使用

    sender.enabled = NO;

    CGFloat labW = 150;
    CGFloat labH = 30;

    CGFloat labX = (self.superview.frame.size.width -labW)*0.5;
    CGFloat labY = (self.superview.frame.size.height - labH) * 0.5;

    //新建一个label并且设置frame
    UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(labX, labY, labW, labH)];
    //把label添加到你控件中
    [self.superview addSubview:label];
    //设置label文字
    label.text = @"正在下载";
    //设置label背影颜色
    label.backgroundColor = [UIColor blackColor];
    //设置文字居中
    label.textAlignment = NSTextAlignmentCenter;
    //设置文字颜色
    label.textColor = [UIColor redColor];
    //设置背影色为透明
    label.alpha = 0;

    //设置圆角

      //1.设置切除半径

    label.layer.cornerRadius = 5;

      //2.切除多余部分

    label.layer.masksToBounds = YES;

    //执行block动画
    [UIView animateWithDuration:1.5 animations:^{
        label.alpha = 0.6;
    } completion:^(BOOL finished) {
        if (finished) {
            //UIViewAnimationOptionTransitionFlipFromLeft这仅仅是动画的一个效果
            [UIView animateWithDuration:1.5 delay:1.0 options:UIViewAnimationOptionTransitionFlipFromLeft animations:^{
                label.alpha = 0.0;
            } completion:^(BOOL finished) {
                [label removeFromSuperview];
                sender.enabled = YES;
            }];
        }
    }];