In Swift 3 we redesigned condition clauses to not use the
wherekeyword; SE-0099 Restructuring Condition Clauses has the details. The upshot is that you can replace
wherein your example with a comma and it’ll work.
Clearly the Learn the Essentials of Swift tutorial should have been updated to account for this; I’d appreciate you file a bug against that, so that the folks responsible can fix this. Please post your bug number, just for the record.
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware
let myEmail = "eskimo" + "1" + "@apple.com"