iOS检查主应用程序或扩展程序

Question

我在我的主app文件中写了这样的内容，也与扩展程序共享。

Detect whether run target is App Extension or iOS App

#ifdef SHARE_EXTENSION
    UIAlertView *alert = [[UIAlertView alloc]initWithTitle:APP_NAME message:@"You only have 1 photo. Confirm deletion? (Please note that you have to submit at least 1 photo for iFeedback)." delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"OK", nil];
    [alert show];
#endif

然而，它仍然给我一个错误，说UIAlertview不能用于扩展。我也需要共享该文件，并且不会仅为此代码创建另一个相同的文件。我该怎么检查？