combinedlets.swift

enum StringPaddingStyle {case Left, Right}

func padStringToLength(
    sourceString: String,
    destinationCount: Int,
    paddingStyle: StringPaddingStyle = .Left,
    paddingCharacter: Character = " "
    ) -> String {

        let
        padCount = destinationCount - sourceString.characters.count,
        padString = String(count: padCount, repeatedValue: paddingCharacter)

        return
            paddingStyle == .Left
                ? padString + sourceString
                : sourceString + padString
}