NSURLSession send parameters with get

Question

I'm trying to parse information from a php, but i need to send a dictionary parameter so i try things ... i saw tutorials,examples but i'm stuck so i went back to the start: (What it's the good way for do this?)

       func asd(){
    let urlPath = "http://xxxxx.php"

    let url: NSURL = NSURL(string: urlPath)

    let request = NSMutableURLRequest(URL: url)
    request.HTTPMethod = "GET"
    var parm = ["id_xxxx": "900"] as Dictionary


    //I THINK MY PROBLEM IT'S HERE! i dont know how to link parm with session, i try is with session.uploadTaskWithRequest(<#request: NSURLRequest?#>, fromData: <#NSData?#>) but doesn't work

    let session = NSURLSession.sharedSession()
    let task = session.dataTaskWithURL(url, completionHandler: {data, response, error -> Void in
        println("Task completed")
        if(error) {
            // If there is an error in the web request, print it to the console
            println(error.localizedDescription)
        }
        var err: NSError?
        var jsonResult = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: &err) as NSDictionary
        if(err?) {
            // If there is an error parsing JSON, print it to the console
            println("JSON Error \(err!.localizedDescription)")
        }
        println(jsonResult.debugDescription)
        let results: NSArray = jsonResult["x"] as NSArray
        dispatch_async(dispatch_get_main_queue(), {
            self.tableData = results
            self.OfertaGridViewLista!.reloadData()
            })
        })
    task.resume()
}

Thanks!

Answer 1

GET data needs to be part of the url's query string. Some methods will accept a dictionary of parameters for POST/PUT requests, but these methods will not add the dictionary to the url for you if you're using the GET method.

If you'd like to keep your GET parameters in a Dictionary for cleanliness or consistency, consider adding a method like the following to your project:

func buildQueryString(fromDictionary parameters: [String:String]) -> String {
    var urlVars:[String] = []
    
    for (k, value) in parameters {
        let value = value as NSString
        if let encodedValue = value.addingPercentEncoding(withAllowedCharacters: NSCharacterSet.urlQueryAllowed) {
            urlVars.append(k + "=" + encodedValue)
        }
    }

    return urlVars.isEmpty ? "" : "?" + urlVars.joined(separator: "&")
}

This method will take a dictionary of key/value pairs and return a string you can append to your url.

For example, if your API requests allow for multiple request methods (GET/POST/etc.) you'll only want to append this query string to your base api url for GET requests:

if (request.HTTPMethod == "GET") {
    urlPath += buildQueryString(fromDictionary: parm)
}

If you're only making GET requests, there's no need to check for which method you'll be using to send your data.

Answer 2

Bit crazy that none of the answers here suggest using NSURLComponents and NSURLQueryItem objects. That is the safest and most modern way to do this.

var iTunesSearchURL = URLComponents(string: "https://itunes.apple.com/search")!
iTunesSearchURL.queryItems = [URLQueryItem(name: "term", value: trackName),
                              URLQueryItem(name: "entity", value: "song"),
                              URLQueryItem(name: "limit", value: "1")]

let finalURL = iTunesSearchURL.url

Answer 3

@paul-mengelt's answer in Objective C:

-(NSString *) buildQueryStringFromDictionary:(NSDictionary *)parameters {
    NSString *urlVars = nil;
    for (NSString *key in parameters) {
        NSString *value = parameters[key];
        value = [value stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLHostAllowedCharacterSet]];
        urlVars = [NSString stringWithFormat:@"%@%@=%@", urlVars ? @"&": @"", key, value];
    }
    return [NSString stringWithFormat:@"%@%@", urlVars ? @"?" : @"", urlVars ? urlVars : @""];
}

Answer 4

Adapted for Swift 3

  static func buildQueryString(fromDictionary parameters: [String:String]) -> String {
    var urlVars:[String] = []

    for (k,value) in parameters {
        if let encodedValue = value.addingPercentEncoding(withAllowedCharacters: CharacterSet.urlQueryAllowed) {
            urlVars.append(k + "=" + encodedValue)
        }
    }

    return urlVars.isEmpty ? "" : "?" + urlVars.joined(separator: "&")
}

Answer 5

fixed objective C function

+(NSString *)buildQueryStringFromDictionary:(NSDictionary *)parameters
{
    NSString *urlVars = @"";
    for (NSString *key in parameters)
    {
        NSString *value = parameters[key];
        value = [value stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLHostAllowedCharacterSet]];
        urlVars = [NSString stringWithFormat:@"%@%@%@=%@", urlVars, urlVars.length ? @"&": @"", key, value];
    }
    return [NSString stringWithFormat:@"%@%@", urlVars ? @"?" : @"", urlVars ? urlVars : @""];
}