NSURLSession: GET Request with parameters swift 2.0

getRequest.swift

//Encode params to be web friendly and return a string. Reference ->http://stackoverflow.com/a/27724627/6091482

extension String {
    
    /// Percent escapes values to be added to a URL query as specified in RFC 3986
    ///
    /// This percent-escapes all characters besides the alphanumeric character set and "-", ".", "_", and "~".
    ///
    /// http://www.ietf.org/rfc/rfc3986.txt
    ///
    /// :returns: Returns percent-escaped string.
    
    func stringByAddingPercentEncodingForURLQueryValue() -> String? {
        let allowedCharacters = NSCharacterSet(charactersInString: "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-._~")
        
        return self.stringByAddingPercentEncodingWithAllowedCharacters(allowedCharacters)
    }
    
}

extension Dictionary {
    
    /// Build string representation of HTTP parameter dictionary of keys and objects
    ///
    /// This percent escapes in compliance with RFC 3986
    ///
    /// http://www.ietf.org/rfc/rfc3986.txt
    ///
    /// :returns: String representation in the form of key1=value1&key2=value2 where the keys and values are percent escaped
    
    func stringFromHttpParameters() -> String {
        let parameterArray = self.map { (key, value) -> String in
            let percentEscapedKey = (key as! String).stringByAddingPercentEncodingForURLQueryValue()!
            let percentEscapedValue = (value as! String).stringByAddingPercentEncodingForURLQueryValue()!
            return "\(percentEscapedKey)=\(percentEscapedValue)"
        }
        
        return parameterArray.joinWithSeparator("&")
    }
}


//Request

class HTTPRequest{
    
    class func request(url: String, parameters: [String: AnyObject],completionHandler: (data: NSData?, response: NSURLResponse?, error: NSError?) -> ()) -> (){
        
        let parameterString = parameters.stringFromHttpParameters()
        let url = NSURL(string: "\(url)?\(parameterString)")!
        let request = NSMutableURLRequest(URL: url)
        request.HTTPMethod = "GET"
        request.setValue("application/json; charset=utf-8", forHTTPHeaderField: "Content-Type")
        
        let task = NSURLSession.sharedSession().dataTaskWithRequest(request){ data, response, error in
            if error != nil{
                print("Error -> \(error)")
               completionHandler(data: nil, response: nil, error: error)
            }else{
                completionHandler(data: data, response: response, error: nil)
            }
        }
        
        task.resume()
    }
}


override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        let params = [
        "APIKEY": "API_KEY",
        "ANOTHERPARAM": "ANOTHERONE"
        ]
        HTTPRequest.request("URLHERE", parameters: params){
            rtn in
            if(rtn.error == nil){
                do {
                    let result = try NSJSONSerialization.JSONObjectWithData(rtn.data!, options: []) as? [String:AnyObject]
                    print("Result -> \(result)")
                } catch {
                    print("Error -> \(error)")
                }
            }else{
                print(rtn.error)
            }
        }
        
    }