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iOS Network Programming with Swift 2 Implementing a Forecast Client Testing the Networking Stack

Mert Kahraman
Mert Kahraman
12,118 Points
Posted by Mert Kahraman
Mert Kahraman
12,118 Points

Everything was fine until carrying the dispatch_async code into APIClient protocol from ViewController

Hi,

Everything on my version was perfectly fine until, about 13:25 on the video, Pasan carried the dispatch_async code into fetch func in APIClient protocol from ViewController.

Error #1 In his version it works, but on mine, the compiler raises an error on the following line:

let task =JSONTaskWithRequest(request) { json, response, error in

It asks me to add self. in front of JSONTaskWithRequest, I guess so because this is inside a closure. As soon as I do this the app won't work properly.

Error #2 The compiler also complains about the task.resume() line at the very bottom of the fetch function. It says: Unresolved identifier of task.

Here is my fetch function:

func fetch<T>(request: NSURLRequest, parse: JSON -> T?, completion: APIResult<T> -> Void) {

    dispatch_async(dispatch_get_main_queue()) {
        let task = JSONTaskWithRequest(request) { json, response, error in

            guard let json = json else { 
                if let error = error {
                    completion(.Failure(error))
                } else {
                    // TODO: Implement Error Handling
                }
                return
            }

            if let value = parse(json) { 
                completion(.Success(value)) 
            } else {
                let error = NSError(domain: TRENetworkingErrorDomain, code: UnexpectedResponseError, userInfo: nil)
                completion(.Failure(error)) 
            }
        }
    }
    task.resume()

}

I would sincerely appreciate your support.

Thanks!

1 Answer

Steven Stanton
Steven Stanton
59,998 Points
Steven Stanton
Steven Stanton
59,998 Points

It looks like you are defining the task inside a closure and then trying to call resume on it outside.

Here is my code: (A bit different because it is Swift 3)

    func fetch<T: JsonDecodable>(request: URLRequest, 
parse: @escaping (Json)->T?, 
completion: @escaping (ApiResult<T>)->Void){


        let task = self.makeJsonTask(with: request){ json, response, error in

            DispatchQueue.main.async {

            guard let json = json else {
                if let error = error{
                    completion(.failure(error))
                }else{
                    //TODO: implement error handling
                }
                return
            }

            if let value = parse(json){
                completion(.success(value))
            }else {
                let error = NSError(domain: StantNetworkingErrorDomain, code: UnexpectedResponseError, userInfo: nil)
                completion(.failure(error))
            }

            }

        }

        task.resume()

    }