Swift's language was unveiled to the swift development team on June 2, 2014. and September 9, 2014 ushered in Swift's second milestone, the swift1.0 version number (GM), which means that no matter whether your application has some functionality written in Swift or the entire application is written in pure Swift. You'll be able to share your results with the world by submitting this app to the Apple store.
You may have noticed that we used the GM code. Rather than final, this is because Swift also continues to incorporate new features to improve performance and redefine syntax.
So from now on. You can confidently use the swift language to write new applications, or use the Swift language to write a part of a feature that has been written to your application. Without worrying about the embarrassment of being rejected by the Apple store because of a language problem.
Swift ushered in the 1.0 GM Edition (2014.09.09)