Can we make an iOS app backward compatible with older iOS versions?
As we can do in android apps using API Levels?
While building an iOS app, the architectures (armv7, armv7s, armv64) you choose dictate what all platforms you will be supporting. The "Deployment target" version that you select in xcode is the minimum OS version that you can support. An iOS app is a universal binary, which means that it can contain code supporting both 32-bit and 64-bit architectures. Building with 64 bit support (iOS 8 SDK) is not the same as dropping support for earlier 32-bit OS versions.