As an example, Xcode 6.4 can't support iOS 9.x, so logically, that means you'd need to accept a lower iOS when using it to build for the store. There were several different SDKs used from Xcode 5.1.1 up to now, so the version of Xcode you use will mandate which SDK and which iOS version(s) you can expect to support.As for Xcode 5.1.1, it's common knowledge that when submitting an app to the store, you can expect to see a dialog alerting to which version Xcode is currently allowed as minimum. At this time, that dialog warns the dev to use Xcode 5.1.1 or higher.
Topic:
App Store Distribution & Marketing
SubTopic:
App Review
Tags: