                 let next = str.character(at:i + 1)
                 
                 if next == ("u" as NSString).character(at: 0) {
-                    var size = ((i - 1) + 12)
+                    let size = ((i - 1) + 12)
                     if (size < len && str.character(at: i + 6) == ("u" as NSString).character(at: 0)){
                         var emoji: NSString? = str.substring(with: NSMakeRange((i), 12)) as NSString?
                         let pos: Data? = emoji?.data(using: String.Encoding.utf8.rawValue)

     - return: TRUE if the authentication was successful or FALSE if it was not.
     */
    open func saveAuthentication(_ aUrl:String,
                                 isCluster:Bool,
                                 authenticationToken:String,
                                 authenticationTokenIsPrivate:Bool,
                                 applicationKey:String,
                                 timeToLive:Int,
                                 privateKey:String,
                                 permissions:NSMutableDictionary?)->Bool{
        /*
         * Sanity Checks.
         */

     * - parameter callback: Callback with error (NSError) and result (NSDictionary) parameters
     */
    open func presence(_ aUrl:String,
                         isCluster:Bool,
                         applicationKey:String,
                         authenticationToken:String,
                         channel:String,
                         callback:@escaping (_ error:NSError?, _ result:NSDictionary?)->Void){
        /*
         * Sanity Checks.
         */
