IOS project showing error “An internal error occurred. Editing functionality may be limited” on xcode 7.1

Question

I just created one new cordova ios project via CLI, and i opened that project in Xcode 7.1 and while running on simulator am getting some error on mainViewController.xib, if

Answer 1

Super specific but one of compile-time errors that can cause this is putting the keyword 'optional' before a function in a non-objc protocol.