encodeURIComponent() in swift

String+EncodeURIComponent.swift

extension String {
    
    func encodeURIComponent() -> String? {
        var characterSet = NSMutableCharacterSet.alphanumericCharacterSet()
        characterSet.addCharactersInString("-_.!~*'()")

        return self.stringByAddingPercentEncodingWithAllowedCharacters(characterSet)
    }
}

// Swift 4

extension String {
    func encodeURIComponent() -> String? {
        var characterSet = CharacterSet.alphanumerics
        characterSet.insert(charactersIn: "-_.!~*'()")
        return self.addingPercentEncoding(withAllowedCharacters: characterSet)
    }
}