60s倒计时（Q群里盆友分享的）

.h

@property (nonatomic, strong)UIButton *verificationCodeButton;

.m

在某个方法里实现

_verificationCodeButton = [UIButton buttonWithType:UIButtonTypeCustom];

_verificationCodeButton.frame = CGRectMake(10, 200, 300, 40);

_verificationCodeButton.backgroundColor = [UIColor grayColor];

[self.view addSubview:_verificationCodeButton];

__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

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

_verificationCodeButton.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];

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

[UIView commitAnimations];

_verificationCodeButton.userInteractionEnabled = NO;

});

timeout--;

}

});

dispatch_resume(_timer);