I just upgraded my macbook OS to Yosemite and updated XCode from 6.0 to 6.1 and now when I build my project and try to run for iPhone 5s with iOS7.0 simulator , it gives me an error saying "iPhone 5s is not available, please select a different device and try again". In XCode 6.0, this was working totally fine.
Following are the build settings for my app
Architecture - Standard Architecture(armv7, arm64)
Base SDK - Latest iOS(iOS 8.1)
Valid architectures - arm64, armv7, armv7s
iOS Deployment Target - iOS6
Found the real answer
The earliest simulator runtime supported on Yosemite is 7.1.