When trying to launch my project to XCode 6.0.1 from Unity 4.5.4f1 I get this error:
Launching iOS project via Xcode4 failed. Check editor log for details.
What am I doing wrong? It says in the Unity 4.5.3 Fixes: iOS: Added Xcode 6 “Build and Run” support.
Hoping for help very soon 
Build and Run apparently isn’t working. Just Build, and then open the project and Run it, is.
Hopefully they’ll fix this soon.
take a look at this - it’s less than ideal, but does work.
http://forum.unity3d.com/threads/nityexception-launching-ios-project-via-xcode4-failed.234557/
Just download the latest patch. The error was fixed at version 4.5.4p1, but 4.5.4p2 is available.
http://unity3d.com/unity/qa/patch-releases
Running Unity on 5.1.1f1 with XCode Version 6.4 (6E35b) on the latest (today’s Patch included) Mac OSX Yosemite still throws that error. Even using the trick from info.plist Update does not work anymore since Unity 5. Any new suggestions on this?
See
That usually works for me. The issue is surfacing each time Unity could not put the compatibility UUID in their plugin because the UUID changed in an Xcode release after the Unity release.
Go to Build Settings and make sure you have selected Symlink Unity libraries.
This was the only thing that worked for me.