iOS开发--验证码

@property (weak, nonatomic) IBOutlet UIButton *l_timeButton;

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- (void)viewDidLoad {

    [super viewDidLoad];

    [_l_timeButton addTarget:self action:@selector(startTime) forControlEvents:UIControlEventTouchUpInside];

}

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-(void)startTime{

    __block int timeout=30; //倒计时时间

    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

    dispatch_source_t _timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0,queue);

    dispatch_source_set_timer(_timer,dispatch_walltime(NULL, 0),1.0*NSEC_PER_SEC, 0); //每秒执行

    dispatch_source_set_event_handler(_timer, ^{

        if(timeout<=0){ //倒计时结束，关闭

            dispatch_source_cancel(_timer);

            dispatch_async(dispatch_get_main_queue(), ^{

                //设置界面的按钮显示 根据自己需求设置

                [_l_timeButton setTitle:@"发送验证码" forState:UIControlStateNormal];

                _l_timeButton.userInteractionEnabled = YES;

            });

        }else{

            int seconds = timeout % 60;

            NSString *strTime = [NSString stringWithFormat:@"%.2d", seconds];

            dispatch_async(dispatch_get_main_queue(), ^{

                //设置界面的按钮显示 根据自己需求设置

                //NSLog(@"____%@",strTime);

                [UIView beginAnimations:nil context:nil];

                [UIView setAnimationDuration:1];

                [_l_timeButton setTitle:[NSString stringWithFormat:@"%@秒后重新发送",strTime] forState:UIControlStateNormal];

                [UIView commitAnimations];

                _l_timeButton.userInteractionEnabled = NO;

            });

            timeout--;

        }

    });

    dispatch_resume(_timer);

}