问题
I created an empty Single View application using Xcode 4.2 on OSX Lion 10.7.2 targeting iPhone 5. The project built happily however when launching the simulator I receive the following error message:
iOS Simulator could not find the SDK. The SDK may need to be reinstalled.
I then tried targeting the iPad with the same results. I removed Xcode using the terminal and downloaded a fresh copy from the AppStore. The clean installation generates the exact same error.
It seems that the SDK is not being deployed during installation. Any advice or tips on how I can correctly install the iOS 5 SDK for the simulator to work?
Update
I downloaded the iOS 4.3 simulator which was not installed. The simulator works perfectly if I select the 4.3 SDK but for some reason is not recognizing the folder containing the 5.0 SDK.
Update
I reformatted the MacBook, reloaded a clean OSX Lion without restoring any backups and installed Xcode. Running the simulator directly after the installed worked, however after a reboot and relaunching Xcode the error came back. The SDK itself seems to have been corrupted. Will try and reinstall Xcode again.
回答1:
After some testing it turns out the problem is caused by a 3rd Party Software. Recently the developer of TotalFinder removed the Asepsis portion of the system and created a separate application for the handling of DS_Store files.
Unfortunately, this breaks the iOS Simulator once installed, and even after uninstalling Asepsis, I needed to rebuild my whole machine to get rid of the error.
Update
BinaryAge is aware of the issue with regards to Xcode 4.2 and it is now listed on the know issues page and a warning banner displayed on the download link.
Final Update
It seems BinaryAge has changed the way Asepsis works and this is no longer an issue with the latest versions.
回答2:
Did you try "File -> Reset Content and Settings ..." in the simulator ? I also encountered the similar problem, but it worked after I reset the simulator! In fact, I also found it worked after I removed all the existing projects and created new ones, but it occurred again after I restart xcode. Fortunately the "Reset" always works for me and I hope it can be helpful for your case.
来源：https://stackoverflow.com/questions/7807719/xcode-4-2-is-missing-the-ios5-sdk-for-the-simulator