swift2 - Cannot invoke `join` with an argument list of type (String, [String]) in Swift 2.0

Question

var specializationTitles = ["a", "b", "c", "d"]
let outputString = join(" / ", specializationTitles)

got an error:

Cannot invoke join with an argument list of type (String, [String])

How to solve this?

Answer 1

let separator = " / "
let outputString = separator.join(specializationTitles)

With Xcode7beta6:

specializationTitles.joinWithString(" / ")

With Xcode7 release version:

specializationTitles.joinWithSeparator(" / ")