URL decode in iOS

To encode and decode urls create this extention somewhere in the project:

Swift 2.0

extension String
{   
    func encodeUrl() -> String
    {
        return self.stringByAddingPercentEncodingWithAllowedCharacters( NSCharacterSet.URLQueryAllowedCharacterSet())
    }
func decodeUrl() -> String
    {
        return self.stringByRemovingPercentEncoding
    }

}

Swift 3.0

 extension String
    {   
        func encodeUrl() -> String
        {
            return self.addingPercentEncoding( withAllowedCharacters: NSCharacterSet.urlQueryAllowed())
        }
    func decodeUrl() -> String
        {
            return self.removingPercentEncoding
        }

    }

Swift 4.1

extension String
{
    func encodeUrl() -> String?
    {
        return self.addingPercentEncoding( withAllowedCharacters: NSCharacterSet.urlQueryAllowed)
    }
    func decodeUrl() -> String?
    {
        return self.removingPercentEncoding
    }
}