ios - 使用类方法添加和删除事件指示器

Question

在我的应用程序中，我有一个处理简单方法的类，因此主要的 UIViewController 上的代码会更少。当我尝试从我的 UIViewController 添加和删除 UIActivityIndi​​cator 时，发生了一件非常奇怪的事情，添加 UIActivityIndi​​cator 没有问题，但是当我尝试删除它(或停止它)时，没有任何反应。

这是我的代码:

这是从主 UIViewController 调用的:

[LoadingView addLoadingView:self.activityIndicator 
         andTheViewToShowIn:self.view];
[ChooseSongDataSourse reloadArrayWithData:self.arrayPlaylist 
                                andReturn:^(NSString *resone) {
    [LoadingView removeLoadingView:self.activityIndicator 
                andTheViewToShowIn:self.view];
    [self.activityIndicator removeFromSuperview];
}];

这是从一个单独的类(“LoadingView”)完成的:

+(void)addLoadingView:(UIActivityIndicatorView *)activityIndicator
   andTheViewToShowIn:(UIView *)viewToShowIn{

    activityIndicator = 
      [[UIActivityIndicatorView alloc]
        initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
    [activityIndicator setCenter:viewToShowIn.center];
    [activityIndicator startAnimating];
    [viewToShowIn addSubview:activityIndicator];
}

+(void)removeLoadingView: (UIActivityIndicatorView *)activityIndicator
  andTheViewToShowIn: (UIView *)viewToShowIn
{
 [activityIndicator removeFromSuperview];
 activityIndicator = nil;
 }

我不是在寻找一个简单的答案，我可以自己做，我是在寻求一种解释，

谢谢! (:

Answer 1

+(UIActivityIndicatorView*)addLoadingViewandTheViewToShowIn: (UIView *)viewToShowIn
  {
     UIActivityIndicatorView* activityIndicator = [[UIActivityIndicatorView     alloc]initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
    [activityIndicator setCenter:viewToShowIn.center];
    [activityIndicator startAnimating];
    [viewToShowIn addSubview:activityIndicator];
    [viewToShowIn bringSubviewToFront:activityIndicator];
    return [activityIndicator autorelease];
  }

+(void)removeLoadingView: (UIActivityIndicatorView *)activityIndicator
  andTheViewToShowIn: (UIView *)viewToShowIn
 {
     [activityIndicator removeFromSuperview];
 }

和:

UIActivityIndicatorView* activityIndicator = [LoadingView addLoadingViewandTheViewToShowIn:self.view];
   [ChooseSongDataSourse reloadArrayWithData:self.arrayPlaylist andReturn:^(NSString *resone) {
      dispatch_async(dispatch_get_main_queue(), ^(){// you can remove it, if you sure that block performed in main-thread
          [LoadingView removeLoadingView:activityIndicator andTheViewToShowIn:self.view];
      });
   }];

你的代码的主要问题是 UIActivityIndi​​catorView 的指针没有从 +(void)addLoadingView:andTheViewToShowIn:;

返回

您可以通过返回参数或指向指针的指针从函数返回对象(就像许多通过采用 NSError** 参数返回 NSError* 的函数)。