-(void)startTime{
__block int timeout= 59; //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.getIdentifyBtn setTitle:@"获取验证码" forState:UIControlStateNormal];
self.getIdentifyBtn.userInteractionEnabled = YES;
});
}else{
// int minutes = timeout / 60;
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
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:1];
[self.getIdentifyBtn setTitle:[NSString stringWithFormat:@"%@秒后重发",strTime] forState:UIControlStateNormal];
[UIView commitAnimations];
self.getIdentifyBtn.userInteractionEnabled = NO;
});
timeout--;
}
});
dispatch_resume(_timer);
}
上面代码的btn是我自己的,看客们根据自己项目来修改,那么还有一个问题,有时候用xib创建了按钮,做了倒计时,你会发现按钮倒计时的时候会发生闪烁的问题,那么解决方法是:
修改你的button的属性,如果是xib很简单,直接到button的属性中把按钮由默认的system改成custom即可,如果是代码创建,在创建的时候用
self.smsButton = [UIButton createButtonWithStyle:UIButtonTypeRoundedRect
withFrame:CGRectMake(80, 0, 100, 30)
withTitle:NSLocalizedString(@"重发验证码", nil)
withTitleColor:color
withBackgroudColor:nil
withNormalImage:nil
withHighlightedImage:nil
withNormalBackgroudImage:nil
}];
不可直接设置buttontype因为buttontype属性是readonly的!!!
原文：http://www.cnblogs.com/changjianioser/p/5076826.html