A valid copy of xcode cannot be found

Visual studio running on my macbook Air cannot see the xcode IOS sdks to run the iphone emulator. I have had it running up untill last night when i did some updates and file changes when it messed up. I have checked the preferences to make sure it was pointing at the correct place first being Library/Frameworks/Xamarin.iOS.framework/Versions/Current. I also just set it to the xcode app and it for some reason starts up the emulator but doesn't build my app onto it. Ive also made sure they're all up to date, uninstalled reinstalled and even completely wiped my laptop and reinstalled vis and xcode with no luck.