IOS实现验证码倒计时功能（二）

 //发送验证码按钮
  _sentCodeBtn = [[UIButton alloc] initWithFrame:CGRectMake(kScreenWidth - 27 - 4 - 94, CGRectGetMinY(_registerCodeFD.frame) + 4, 94, 40)];
  [_sentCodeBtn setBackgroundColor:colorWithRGBA(0, 191, 191, 0.9)];
  [_sentCodeBtn setTitle:@"发送验证码" forState:UIControlStateNormal];
  [_sentCodeBtn.titleLabel setFont:[UIFont systemFontOfSize:13.0f]];
  //设置圆角
  [_sentCodeBtn.layer setCornerRadius:3.0f];
  [_sentCodeBtn.layer setShouldRasterize:YES];
  [_sentCodeBtn.layer setRasterizationScale:[UIScreen mainScreen].scale];
  //发送事件
  [_sentCodeBtn addTarget:self action:@selector(sentCodeMethod) forControlEvents:UIControlEventTouchUpInside];
  [self.view addSubview:_sentCodeBtn];

//发送验证码
-(void)sentCodeMethod{
 NSLog(@"发送验证码。。");
 //计时器发送验证码
 [self sentPhoneCodeTimeMethod];
 //调用发送验证码接口-》

}

//计时器发送验证码
-(void)sentPhoneCodeTimeMethod{
 //倒计时时间 - 60秒
 __block NSInteger timeOut = 59;
 //执行队列
 dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
 //计时器 -》dispatch_source_set_timer自动生成
 dispatch_source_t timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
 dispatch_source_set_timer(timer, DISPATCH_TIME_NOW, 1.0 * NSEC_PER_SEC, 0 * NSEC_PER_SEC);
 dispatch_source_set_event_handler(timer, ^{
  if (timeOut <= 0) {
   dispatch_source_cancel(timer);
   //主线程设置按钮样式-》
   dispatch_async(dispatch_get_main_queue(), ^{
    [_sentCodeBtn setTitle:@"发送验证码" forState:UIControlStateNormal];
    [_sentCodeBtn setUserInteractionEnabled:YES];
   });
  }else{
   //开始计时
   //剩余秒数 seconds
   NSInteger seconds = timeOut % 60;
   NSString *strTime = [NSString stringWithFormat:@"%.1ld",seconds];
   //主线程设置按钮样式
   dispatch_async(dispatch_get_main_queue(), ^{
    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:1.0];
    [_sentCodeBtn setTitle:[NSString stringWithFormat:@"%@S后重新发送",strTime] forState:UIControlStateNormal];
    [UIView commitAnimations];
    //计时器件不允许点击
    [_sentCodeBtn setUserInteractionEnabled:NO];
   });
   timeOut--;
  }
 });
 dispatch_resume(timer);
}