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iOS Build a Weather App with Swift Managing Complexity Methods with Closures

Posted by Dulio Denis
Dulio Denis
14,457 Points

NSJSONObjectWithData Updated with Swift 2

Looks like they have updated the NSJSONObjectWithData after WWDC15 with Swift 2 and this now needs to catch a throw for error handling.

Anyone know the new syntax?

Kristofer Doman
Kristofer Doman
18,307 Points

Nothing is updated with Swift 2 yet unless you're running a beta version of Xcode, which you probably shouldn't be doing if you're doing these lessons. Just a heads up.

Nure México
Nure México
25,840 Points

I’m also looking forward to the answer to this. I’m using Xcode beta with Swift 2. And yes now it suggest to use a try catch.

3 Answers

Will Matthews
Will Matthews
8,127 Points
Will Matthews
Will Matthews
8,127 Points

Looks like the Swift 2 approach is to use the new do-try-catch approach. Here's what worked for me:

    do {
        let jsonDictionary = try NSJSONSerialization.JSONObjectWithData(data!, options: []) as! [String: AnyObject]
        completion(jsonDictionary)
    } catch let error {
        print("JSON Serialization failed. Error: \(error)")
    }
Nathan Tallack
Nathan Tallack
22,160 Points
Nathan Tallack
Nathan Tallack
22,160 Points

Thank you thank you thank you thank you!!!!!! :)

Zoli Honig
Zoli Honig
805 Points
Zoli Honig
Zoli Honig
805 Points

Hi guys! After poking around, I was able to figure this one out. You just have to add "try!" before NSJSONSerialization. It should look like this.

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

Hope this helps!

TheBigoso /\
TheBigoso /\
3,217 Points

Hey man...you saved me from pulling the last bit of hair out of my head! It works!!!!!

Ramesh VJ
Ramesh VJ
2,201 Points
Ramesh VJ
Ramesh VJ
2,201 Points

I tried both the approach of Will and Zoli, the error got fixed, but when I went ahead with accessing data from web exercise, the label is not updating from web.

when I used the print statement, for both the approach the completion is not getting executed

func downloadJSONFromURL(completion: JSONDictionaryCompletion ){

    let request: NSURLRequest = NSURLRequest(URL: queryURL)

    let dataTask = session.dataTaskWithRequest(request){
        (let data, let response, let error) in


        if let httpResponse = response as? NSHTTPURLResponse{

            switch(httpResponse.statusCode){
            case 200:

                 print("getting positive response +++")

                /*do {

                    print("getting positive response 2+++")

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

                    print("getting positive response 4 ")

                } catch let error {
                    print("JSON Serialization failed. Error: \(error)")
                }*/


                let jsonDictionary = try!NSJSONSerialization.JSONObjectWithData(data!, options:[]) as? [String: AnyObject]
                 print("getting positive response 4 ")
                 completion(jsonDictionary)

            default:
                print("GET request not successful. HTTP status code: \(httpResponse.statusCode)")
            }
        }else{
            print("Error: Not a valid HTTP response")
        }
    }

    dataTask.resume()
}