I have upgraded my iPhone to iOS 6, however I am currently on Xcode 4.2 (on Snow Leopard). Now I am getting this error message:
The version of iOS on “xxx xxx” does not match any of the versions of iOS supported for development with this installation of the iOS SDK. Please restore the device to a version of the iOS listed below, or update to the latest version of the iOS.
Is it possible to restore my iPhone to older version say 5.1 or some how make my Xcode to support/recognize iOS6?
I followed the following steps, to resolve my issue by making Xcode to support iOS 6:
1.First download Xcode 4.5 .dmg file from Here (You would need developer account).
2.Then mount this image and use "Show Package Contents" from context menu.
3.Then copy the following folder
Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/6.1 (10A403)
to your mac's following folder (This path may differ from mac to mac based on its version. On Snow Leopard you may find the Developer folder in Finder under PLACES section, and probably on Lion, you have to right click the Xcode.app and have to use Show Package Contents):
Developer/Platforms/iPhoneOS.platform/DeviceSupport
4.Similarly copy the iOS 6 SDK folder from following directory:
Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.0.sdk
to your mac's following folder
Developer/Platforms/iPhoneOS.platform/Developer/SDKs
5.Also copy version.plist from Contents/Developer/Platforms/iPhoneOS.platform folder to your mac's Developer/Platforms/iPhoneOS.platform folder.
6.Re-start Xcode and re-connect the device(s).
Bingo !! now Xcode supports recognizes iOS6 device(s) and even I am able to run and debug my app (built for older SDKs) on my iPhone with iOS6 (I am not sure about iPhone 6.0 simulator though).
However, answer to How to restore iPhone to older version say 5.1 is still pending.
You cant debug iO6 device in Xcode 4.2. iO6 device debugs only in Xcode 4.5 (latest one). And most importent for installing Xcode 4.5, in your machine must have at least Lion Operating System.For efficiently debugging of iOS device, You must upgrade your OS.
I had the exactly same problem !
Downgrading iOS 6 in your iPhone is not officially supported by Apple anymore :
https://discussions.apple.com/thread/4533316?start=0&tstart=0
What works for me was to install Lion in an external HD USB, upgrade Xcode to the latest version and upgrade the Provisioning Profiles in my Apple Developer account for this environment.
Upgrade to Xcode 4.5 (and OSX mountain lion). No previous version of Xcode supports iOS 6. You can also check if you can restore your phone using a previous version of iOS by getting the .ipsw file and option-clicking on "restore" button when selecting your device on iTunes.
来源：https://stackoverflow.com/questions/12621481/iphone-with-ios-6-and-xcode-4-2-issue