I can't find a String.CharacterView method that returns first letter as String in the documentation. Any luck anyone?

Hey Patrick,

Couple little issues with your code:

1. You need to put that function outside the String extension. We're declaring a function, not a method on String that itself takes a String. Think about how you'd call that, and you'll see why: "Greg".firstLetter(word: "Greg") doesn't make sense. Instead, with a plain old function, we just call firstLetter(word: "Greg")
2. You can't assume that the first character is just index 0, because strings are a pain in the . There are entire WWDC videos explaining why, but here's one example: The character é could be either one or two characters, depending on the encoding (here's a bit of podcast talking about this exact thing). So, instead, you should use the string property startIndex.

Here's a solution, not changing much from your code:

// Enter your code below
extension String {

  func modify(function: String -> String) -> String {
    return function(self)
  }

}

func firstLetter(word: String) -> String {
    let characters = word.characters
    let firstCharacter = characters[word.startIndex]
    return String(firstCharacter)
}

In fact, though, we don't need the characters property at all. We can index directly into the string using startIndex:

// Enter your code below
extension String {

  func modify(function: String -> String) -> String {
    return function(self)
  }

}

func firstLetter(word: String) -> String {
    return String(word[word.startIndex])
}

Cheers

-Greg