> In the meantime, I'm thinking of reverting to Xcode 7.3 and running the two versions side by side... Is that possible ?
I think you're probably better off just keeping Xcode 8 by itself, but use Swift 2.3 for projects if you need to. There are very very few differences between 2.2 and 2.3, converting existing code over is much faster than 2.2 -> 3.0.
Tried that, but it seems the build setting now needs an explicit SWIFT_VERSION configured .. And carthage dependencies don't have that so the build fails.
Basically, I couldn't get my carthage dependencies to compile with Swift 2.3, so I went the Swift3 route, which now, after 10 hours wasted, was such a bad idea!
Appstore was bugging me to update Xcode so I caved in and now I'm stuck with a project that doesn't build and the deadline approaching fast. Such a useless waste of time.
I think you're probably better off just keeping Xcode 8 by itself, but use Swift 2.3 for projects if you need to. There are very very few differences between 2.2 and 2.3, converting existing code over is much faster than 2.2 -> 3.0.