Truncate Swift 3 by words or something else

// Vladimir Zhelnov - neatek.pw - Web/iOS dev
extension String {
    func truncate2(length: Int, wordSeparator: String = " ", trailing: String = "…") -> String {
        if self.characters.count > length {
            let words = self.components(separatedBy: wordSeparator)
            var cumulativeCharacters = 0
            var wordsToInclude:[String] = []
            for word in words {
                cumulativeCharacters += word.lengthOfBytes(using: String.Encoding.utf8) + 1
                if cumulativeCharacters < length {
                    wordsToInclude.append(word)
                } else {
                    return wordsToInclude.joined(separator: wordSeparator) + trailing
                }
            }
            return self.substring( to: self.index(self.startIndex, offsetBy: length) ) + trailing
        } else {
            return self
        }
    }
}