Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

iOS

Posted by Tukang Keboen
Tukang Keboen
2,840 Points

Cannot invoke 'dataTaskWithRequest' with an argument list of type '(NSURLRequest,(_,_,_),_) throws -> _)

func downloadJSONFromURL(completion: JSONDictionaryCompletion) {

    let request: NSURLRequest = NSURLRequest(URL: queryURL)
    let dataTask = session.dataTaskWithRequest(request) {
        (let data, let response, let error) in

        // 1. Check HTTP response for successful GET request

        if let httpResponse = response as? NSHTTPURLResponse {
            switch(httpResponse.statusCode) {
            case 200:
                // 2. Create JSON object with data
                let jsonDictionary = try NSJSONSerialization.JSONObjectWithData(data!, options: []) as! [String:AnyObject]
                completion(jsonDictionary)
            default:
                print("GET request not successful HTTP status code: \(httpResponse.statusCode)")
            }

        } else {
            print("Error: Not a valid HTTP response")
        }



    }
    dataTask.resume()

}

}

1 Answer

Tori Sambrooks
Tori Sambrooks
3,896 Points
Tori Sambrooks
Tori Sambrooks
3,896 Points

func downladJSONfromURL(completion: JSONDictionaryCompletion){

let request: NSURLRequest = NSURLRequest(URL: queryURL)
let dataTask = session.dataTaskWithRequest(request) {
    (let data, let response, let error) in

    //1. Check HTTP response for succesful GET request

    if let httpResponse = response as? NSHTTPURLResponse {

        switch(httpResponse.statusCode) {
        case 200:

    //2. Create JSON object with data
            let jsonDictionary = NSJSONSerialization.JSONObjectWithData(data, options: nil, error: nil) as? [String: AnyObject]
            completion(jsonDictionary)
        default:
            println("GET request not succesful. HTTP status code: \(httpResponse.statusCode)")


        }

    } else {
        println("Error: Not a valid HTTP response")
    }

    }

    dataTask.resume()

}

The mistakes that I as able to identify were that

let jsonDictionary = try NSJSONSerialization.JSONObjectWithData(data!, options: []) as! [String:AnyObject]

should be

let jsonDictionary = NSJSONSerialization.JSONObjectWithData(data, options: nil, error: nil) as? [String: AnyObject]

and also

print("GET request not successful HTTP status code: (httpResponse.statusCode)")

Should be

println("GET request not succesful. HTTP status code: (httpResponse.statusCode)")

Hope this helps!