I hope someone has some thoughts on this one...
I have a project that uses UIManagedDocument. The first thing I do in the appDelegate is open the document. Everything has been going fine until suddenly (nothing was changed in the code) the -openWithCompletionHandler: stopped executing the handler code. The app works just fine on the device, but not in the simulator. As a lark I tried running the app under the iOS 5.0 and 6.0 simulators and everything works as expected!?!
I have reinstalled xcode 4.5 and the behavior stays the same. I deinstalled by trashing the xcode app in the applications folder. I also deleted all the iPhone simulator files in the ~/Library/Application Support/iPhone Simulator/ directory.
Anyone have any thoughts?
来源：https://stackoverflow.com/questions/12577672/uimanageddocument-completionhandler-not-executed-in-ios-5-1-simulator-but-works