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iOS Closures in Swift 2 First Class Functions Higher Order Functions

16,353 Points

Closures - Challenge Task 3 of 3. How does this code know to return the first letter in a string?

This code works but it just seems like you'd have to use 'index' or 'characters.first' at some point in the function. The for loop seems like it will return all characters, not just the first character.

// Enter your code below
extension String {
    func modify(result: String -> String) -> String {
        return result(self)


func firstLetter(letter: String) -> String {
    for character in letter.characters {
        return "\(character)"
    return ""

let value = "Swift".modify(firstLetter)

1 Answer

Jennifer Nordell
Jennifer Nordell
Treehouse Teacher

The key here is to remember that once a return statement is hit the function exits. Since it starts a for loop it's going to go to the first character and then return it. And then the function exits. So it never makes it to the second letter :smiley: