倒计时

学习别人的一个方便快捷的倒计时实现 

__block int timeout = time; //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

//[self.phoneLoginVC.sendCode setTitle:@"发送验证码" forState:UIControlStateNormal];

//self.phoneLoginVC.sendCode.userInteractionEnabled = true;

});

}else{

int seconds = timeout % 61;

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

[UIView beginAnimations:nil context:nil];

[UIView setAnimationDuration:1];

//[self.phoneLoginVC.sendCode setTitle:[NSString stringWithFormat:@"%@秒",strTime] forState:UIControlStateNormal];

[UIView commitAnimations];

//self.phoneLoginVC.sendCode.userInteractionEnabled = false;

});

timeout--;

}

});

dispatch_resume(_timer);