How to get random element from a set in Swift?
Probably the best approach is advance which walks successor for you:
func randomElementIndex<T>(s: Set<T>) -> T { let n = Int(arc4random_uniform(UInt32(s.count))) let i = advance(s.startIndex, n) return s[i]}(EDIT: Heh; noticed you actually updated the question to include this answer before I added it to my answer... well, still a good idea and I learned something too. :D)
You can also walk the set rather than the indices (this was my first thought, but then I remembered advance).
func randomElement<T>(s: Set<T>) -> T { let n = Int(arc4random_uniform(UInt32(s.count))) for (i, e) in enumerate(s) { if i == n { return e } } fatalError("The above loop must succeed")}