Is it possible to compile Latest Swift version on older Xcode?

Question

For instance, I would play around Swift 4.2, but I don't want to use Xcode 10 beta version, I have Xcode 9.4.1.

I wonder if there is any way do it, is it possible?

Answer 1

I figured it out that Yes it is possible. You can achieve it by installing the latest Snapshot:

Development Snapshots are prebuilt binaries that are automatically created from mainline development branches.

_{https://swift.org/download/#snapshots}

Snapshot is a toolchain that you can install into Xcode which contains the latest compiler, leading to let you able to build your app on the latest tools.

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How to setup a snapshot into Xcode?

1- Download the latest snapshot (Xcode) from Swift website.

2- Install the downloaded snapshot .pkg file.

3- Run Xcode and then go to: Xcode -> Toolchains -> Manage toolchains.

4- After selecting "Components" - "Toolchains" options, you should see:

Select "Swift Developer Snapshot" and thats it! You might need to reset Xcode after doing the above steps.

Reminder: You should reselect "Xcode 8.3.3" option after done playing around Swift 4, as mentioned in Swift - Using Downloads section:

To submit to the App Store you must build your app using the version of Swift that comes included within Xcode.

Answer 2

Although it is not directly from the Xcode, you could also use the Iswift which should has the latest swift version (latest snapshot).