Completion handlers in Swift 3.0

Question

I am using the code below to sync data with my server. After completing the task, I would like to call:

self.refreshControl?.endRefreshing()

<

Answer 1

Swift 4:

1. Create a completion block.

   func getDataFromJson(url: String, parameter: String, completion: @escaping (_ success: [String : AnyObject]) -> Void) {
   
       //@escaping...If a closure is passed as an argument to a function and it is invoked after the function returns, the closure is @escaping.
   
       var request = URLRequest(url: URL(string: url)!)
       request.httpMethod = "POST"
       let postString = parameter
   
       request.httpBody = postString.data(using: .utf8)
       let task = URLSession.shared.dataTask(with: request) { Data, response, error in
   
           guard let data = Data, error == nil else {  // check for fundamental networking error
   
               print("error=\(error)")
               return
           }
   
           if let httpStatus = response as? HTTPURLResponse, httpStatus.statusCode != 200 {  // check for http errors
   
               print("statusCode should be 200, but is \(httpStatus.statusCode)")
               print(response!)
               return
   
           }
   
           let responseString  = try! JSONSerialization.jsonObject(with: data, options: .allowFragments) as! [String : AnyObject]
           completion(responseString)
   
   
   
       }
       task.resume()
   }
   

2. Call method

   getDataFromJson(url: "http://example.com", parameter: "vehicle_type=Car", completion: { response in
           print(response)
   
       })