After installing Xcode 7 I can't build and run projects anymore as document fails to open

Question

EDIT: This question refers to teh pre-release version of Xcode 7, hence it may not be relevant if you are running the currently released version as some issues may have been

Answer 1

Verify you have the latest Xcode Beta installation with Xcode-beta open click "About Xcode" and check the build number.

Then check the Current build number of the latest Xcode-beta on the Xcode Downloads Page:

https://developer.apple.com/xcode/downloads/