Get string initials Swift

StringInitials.swift

extension String {
  public var initials: String {
    var finalString = String()
    var words = components(separatedBy: .whitespacesAndNewlines)
    
    if let firstCharacter = words.first?.first {
      finalString.append(String(firstCharacter))
      words.removeFirst()
    }
    
    if let lastCharacter = words.last?.first {
      finalString.append(String(lastCharacter))
    }
    
    return finalString.uppercased()
  }
}