I get the error “Swift Language Version” (SWIFT_VERSION) is required to be configured correctly for targets which use Swift. Use the [Edit > Convert > To Current Swift Syntax…] menu to choose a Swift version or use the Build Settings editor to configure the build setting directly.
I have a project with an iOS app, a Today extension, a Watch extension and a complication. For the Today and Watch extension I get this error. I have tried both solutions suggested, but there is nothing to convert, and the SWIFT_VERSION says "Swift 4.0 (unsupported)" for all targets.
