UIView，动画，完成块，UIAlertView答案

【问题标题】：UIView, animate, completionblock, UIAlertViewUIView，动画，完成块，UIAlertView
【发布时间】：2013-10-23 00:41:30
【问题描述】：

我有一个带有登录屏幕的应用程序，其中包含一个登录按钮和一个注册按钮，如果我检测到我无法访问互联网，我会通过显示覆盖视图来隐藏这些按钮

 self.coveringview

现在我用这个视图的 alpha 做一些简单的动画，一旦完成，我希望弹出一个 alertview 来告诉用户发生了什么，在这段代码中你可以看到我通过发出警报来做到这一点。显示在 animatewithduration 的完成块中。

bahvior 不是我想要的，警报弹出太快而没有向用户显示我希望它显示的淡出，我该怎么办？

NetworkStatus netStatus = [reachability currentReachabilityStatus];
if(netStatus == NotReachable) {
   UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"No Internet Connection"
                                                  message:@"Unable to connect to the server.  
     Please check your internet connection and try again."
                                                 delegate:self
                                        cancelButtonTitle:nil
                                        otherButtonTitles:@"OK", nil];
  [UIView animateWithDuration:1.0
                         animations:^{
                                self.coveringView.alpha = 1.0;
                         }completion:^(BOOL finished) {
                             // this is the problem here, I need to make this alert show up after  
                             the fade out occurs completely
                             [alert show];
                             self.coveringView.hidden = NO;
                         }];
}
else {
  [UIView animateWithDuration:1.0
                   animations:^{
                      self.coveringView.alpha = 0.0;
                   }completion:^(BOOL finished) {
                      self.coveringView.hidden = YES;
                   }];
}

【问题讨论】：

标签： ios objective-c uiview uialertview

【解决方案1】：

从 Interface Builder 中删除您的 self.coveringView.hidden = YES 并仅设置 alpha = 0

NetworkStatus netStatus = [reachability currentReachabilityStatus];
if(netStatus == NotReachable) {
   UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"No Internet Connection"
                                                  message:@"Unable to connect to the server.  
     Please check your internet connection and try again."
                                                 delegate:self
                                        cancelButtonTitle:nil
                                        otherButtonTitles:@"OK", nil];

    [UIView animateWithDuration:1.0
                     animations:^{
                            self.coveringView.alpha = 1.0;
                     }completion:^(BOOL finished) {
                         // this is the problem here, I need to make this alert show up after  the fade out occurs completely
                      if(finished){
                         [alert show];
                      }
                     }];                     



}
else {
  [UIView animateWithDuration:1.0
                   animations:^{
                      self.coveringView.alpha = 0.0;
                   }completion:^(BOOL finished) {
                      if(finished){
                      self.coveringView.hidden = YES;
                      }
                   }];

【讨论】：

还是不行，弹出太快，我觉得这里多线程可能有问题？？
还是不做，我觉得还得再拖延一下。
尝试在完成块内初始化alertview
你能帮我做最后一次尝试吗，我会在几分钟内编辑答案
让我们continue this discussion in chat

【解决方案2】：

您不需要同时使用 setHidden 和 0.0 的 alpha 它们都会使视图不会拦截触摸。您的 hidden/notHidden 可能与 alpha 更改发生冲突。

尝试像这样简化：

NetworkStatus netStatus = [reachability currentReachabilityStatus];
if(netStatus == NotReachable) {
   UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"No Internet Connection"
                                                  message:@"Unable to connect to the server.  
     Please check your internet connection and try again."
                                                 delegate:self
                                        cancelButtonTitle:nil
                                        otherButtonTitles:@"OK", nil];
  [UIView animateWithDuration:1.0
                         animations:^{
                                self.coveringView.alpha = 1.0;
                         }completion:^(BOOL finished) {
                             //I need to make this alert show up after the fade out occurs completely
                             [alert show];
                         }];
}
else {
  [UIView animateWithDuration:1.0
                   animations:^{
                      self.coveringView.alpha = 0.0;
                   }completion:^(BOOL finished) {
                   }];
}

【讨论】：

嗨，这是对另一个主题的简化，但没有解决最初的问题，警报仍然突然出现。