A simple function that reverses a string. It demonstrates the use of "inout" variables and Array's "reduce" method. The use of "inout" here also demonstrates that you can still use value types in place of reference types without loosing the ability to have functions updating the actual variable values.

reverseString.swift

func reverseString(inout string: String) {
    var chars = Array(string.characters)
    var temp: Character!
    for i in 0..<chars.count/2 {
        temp = chars[i]
        chars[i] = chars[chars.count - (i + 1)]
        chars[chars.count - (i + 1)] = temp
    }
    string = chars.reduce("") {$0 + "\($1)"}
}

var name = "Hello World"
reverseString(&name)

print(name)
// prints "dlroW olleH"

// A more concise version using the built-in reverse() method
func reverseString(inout string: String) {
    string = string.characters.reverse().reduce("") {$0 + "\($1)"}
}