__block NSInteger timeout= ; //倒计时时间 KWeakSelf dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, ); dispatch_source_t _timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, , ,queue); dispatch_source_set_timer(_timer,dispatch_walltime(NULL, ),1.0*NSEC_PER_SEC, ); //每秒执行 dispatch_source_set_event_handler(_timer, ^{ if(timeout < ){ //倒计时结束,关闭 dispatch_source_cancel(_timer); dispatch_async(dispatch_get_main_queue(), ^{ KStrongSelf //设置界面的按钮显示 根据自己需求设置 self.getCodeBtn.enabled = YES; [self.getCodeBtn setTitle:@"获取验证码" forState:UIControlStateNormal]; }); }else{ self.getCodeBtn.enabled = NO; NSString *strTime = [NSString stringWithFormat:@"%zd秒",timeout]; dispatch_async(dispatch_get_main_queue(), ^{ //设置界面的按钮显示 根据自己需求设置 [self.getCodeBtn setTitle:strTime forState:UIControlStateNormal]; }); timeout--; } }); dispatch_resume(_timer);