Updating Xcode to 4.5 and your iPhone device to 6.0 you might run into this error where you cannot run your application on your device.
Xcode cannot run using the selected device. No provisioned iOS device are available with a compatible iOS version. Connect an iOS device with a recent enough version of iOS to run your application or choose an iOS simulator as the destination.
The error can be due to two things. First in the project summary select the correct Deployment Target. E.g 6.0.
The other issue is due to you having restored your phone and the iPhone is not set to development. To fix this go to Organizer, plug in your phone if not already and select the phone under Devices. Here press the button “Use for Development“.