您无法写入应用包，由于沙箱的限制（这也会破坏您的代码签名）。您应该改为写入应用程序的documents目录。

You cannot write into your app bundle, because of sandbox restrictions (it would also break your code signature). You should write to your app's documents directory instead.

您可以使用以下命令获取Documents目录：

You can get your Documents directory with:

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
NSString *docPath = [paths objectAtIndex:0];