Callback function syntax in Swift
Rob's answer is correct, though I'd like to share an example of a simple working callback / completion handler, you can download an example project below and experiment with the getBoolValue's input.
Swift 5:
func getBoolValue(number : Int, completion: (Bool)->()) { if number > 5 { completion(true) } else { completion(false) }}getBoolValue(number: 2) { (result) -> () in // do stuff with the result print(result)}Important to understand:
(String)->() // takes a String returns void()->(String) // takes void returns a String