__block int timeout=60;

//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

codeLabel.text = @"获取验证码";

codeLabel.userInteractionEnabled = YES;

});

}else{

int seconds = timeout % 60;

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

if ([strTime isEqualToString:@"0"]) {

strTime = [NSString stringWithFormat:@"%d",60];

}

dispatch_async(dispatch_get_main_queue(), ^{

//设置界面的按钮显示 根据自己需求设置

[UIView beginAnimations:nil context:nil];

[UIView setAnimationDuration:1];

codeLabel.text = [NSString stringWithFormat:@"%@", [NSString stringWithFormat:@"%@秒",strTime]];

[UIView commitAnimations];

codeLabel.userInteractionEnabled = NO;

});

timeout--;

}

});

dispatch_resume(_timer);