Function Argument Unwrap Optional

functions.playground

func myFunc1(name: String!) {
    println(name);              // playground shows "Jon1" is printed
}

func myFunc2(name: String) {
    println(name);              // playground shows "Jon2" is printed
}

let str1:String? = "Jon1";      // playground shows str1 is {Some "Jon1"}
let str2:String = "Jon2";       // playground shows str2 is "Jon2"

myFunc1(str1);
myFunc2(str2);


/* if you do this, though, you'll get an error because you're passing in an optional that's never being unwrapped */

func myFunc3(name: String) {
    println(name);
}
let str3:String? = "Jon3";
myFunc2(str3);                  // error: Value of optional type String? not unwrapped; did you mean to use '!' or '?'?