How to build Swift 3 project on Xcode 9?

ios xcode swift3 swift4 xcode9
Exey Panteleev picture Exey Panteleev · Jun 6, 2017 · Viewed 43.7k times · Source

Xcode 9 Release Notes says that Swift 3 compilation is supported:

One compiler for Swift 4 and Swift 3, Swift 4 and Swift 3 targets can be compiled together in the same project.

I have installed Xcode 9 beta. But when I press Build it shows bunch of errors. Are some special preparations need to do when use Swift 3 in Xcode 9?

UPD: Module compiled with Swift 3.1 cannot be imported in Swift 4.0

Module compiled with Swift 3.1 cannot be imported in Swift 4.0

Answer

vadian picture vadian · Jun 6, 2017

Select the target, goto Build Settings > Swift Language Version:

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