IsHexColorString.swift

extension String {
  var isHexColorString: Bool {
    do {
      let regex = try NSRegularExpression(pattern: "^#?[0-9A-Fa-f]{6}$")
      return regex.matches(in: self, options: [], range: wholeRange).isEmpty == false
    } catch {
      return false
    }
  }
}

extension String {
  var wholeRange: NSRange {
    return NSRange(location: 0, length: self.count)
  }
}