Can I submit code written in Swift 4 to the App Store with Xcode 8.3.2?

Question

I would like to use the Xcode 9 beta for use in development but I can't seem to get the correct settings for using Swift 3.2 within Xcode 9. The editor is much quicker than Xcode 8.3.2

I can (and have) downloaded the Swift 4 toolchain from swift.org and can use it from within both Xcode 8.3 and the Xcode 9 beta. If I wanted to ship my app before Xcode 9 is officially released, could I write it in Swift 4 and then submit it to the App Store via Xcode 8.3 using the Swift 4 toolchain?

Answer 1

No, you cannot submit a binary that contains code built with the Swift 4 toolchain (or any development toolchain for that matter) to the Apple App Store using Xcode 8.3.2.

Jordan Rose, a Swift compiler engineer at Apple, tweeted:

Development toolchains are never used when submitting to the store, sorry! (We want to avoid XcodeGhost-like scenarios.)

Thus, this configuration is not supported and you will need to wait for Xcode 9 to ship projects using Swift 4. Your binary will be rejected.