"The file "MyApp.app" couldn't be opened because you don't have permission to view it" when running app in Xcode 6 Beta 4
Having the problem on DEVICE too (not just simulator)?
The other solutions only fixed it for me on simulator, not device.
For me this problem occurred (in Xcode 6) when I would try to change the main info.plist properties whilst trying to change my app name.
In info.plist I had changed Executable File
name to something other than the default ${EXECUTABLE_NAME}
...
I had mistaken this field for the field that changes the name of the app under the icon on the springboard.