If you need to stay with Xcode 4.3 and you’re not ready to make the 4.5 jump, be very careful when upgrading your devices to iOS 6 (i.e. consider not doing it).
Yesterday, I upgraded my iPhone 4 to iOS 6 and now my current version of Xcode (4.3.3) cannot deploy to it.
I completely forgot that Xcode has this limitation. It’s similar to a situation that I encountered a while back when I upgraded my devices to iOS 5, but that was worse because at that time I couldn’t upgrade to Xcode 4.3 because my MacBook Pro had a Core Duo processor and could not be upgraded to Lion (Xcode 4.3 required Lion). Unfortunately, the development team I’m working with is sticking with Xcode 4.3 for the time being so that means my iPhone can’t be used for testing now.
This is really annoying.