iOS Compatibility on different iOS Operation Systems

Question

I wanted to ask how compatibility on different iOS operation systems works in iOS. For example If I develop an app on Xcode 9.2 and Swift 4 for i

Answer 1

Yes, it will work on iOS9 With Xcode 9.2 and swift4 you can develop an application for ios8.0 and above.

In your project setting, you have to select your development target