iOS 8.2 not supported in Xcode 6.3 beta
After installing Xcode 6.2 also released this days, I opened a random project, it signed (or did something with my device) and after that Xcode 6.3 beta recognised my iOS 8.2 version!
- Install the last stable Xcode version
- open a random project
- connect your device while keeping the Xcode opened
- let Xcode make it's own procedures for recognising the device ("copy symbols"..)
- open your beta Xcode and enjoy using your test device as always