Drop the current HTTP request in URLSession using swift 3

Drop Request

In most of the time user switch between one page to another or one controller to another using tab bar icon without waiting for its result. due to this reason multiple network request ongoing and application becomes slow, it’s better to dismiss all its previous network request and keep only current network request so we can get the data fast. here I have taken the example of URLSession request:

1: Define the global class where we have to make a network request and with the help of delegate method, we can get the data to the respective class.

2: Lets we have a global class like:

func callingHttpPostMethod (params:String,apiname : String ,signalName: String){
    
    let defaults = UserDefaults.standard;
    let urlString  = BASE_DOMAIN + apiname
    
    print("url  %@",urlString);
    print("params  %@",params);
    
    //queue.async {
    var request = URLRequest(url: URL(string: urlString)!)
    request.httpMethod = "POST"
    let postString = params;
    request.httpBody = postString.data(using: .utf8)
    
    
    if defaults.object(forKey: "authKey") == nil{
        request.addValue("", forHTTPHeaderField: "authKey")
        request.addValue(API_USER_NAME, forHTTPHeaderField: "apiKey")
        request.addValue(API_KEY, forHTTPHeaderField: "apiPassword")
    }
    else{
    request.addValue(defaults.object(forKey: "authKey") as! String, forHTTPHeaderField: "authKey")
    request.addValue(API_USER_NAME, forHTTPHeaderField: "apiKey")
    request.addValue(API_KEY, forHTTPHeaderField: "apiPassword")
    }
    
    
    task = URLSession.shared.dataTask(with: request) { data, response, error in
        guard let data = data, error == nil else {                                                 // check for fundamental networking error
            print("error=\(String(describing: error))", "aaa",error)

            if let error = error as NSError?, error.domain == NSURLErrorDomain && error.code == NSURLErrorCancelled {
            }
            else{
            DispatchQueue.main.async {
            self.sendingErorReport();
            }
            }
            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 = \(String(describing: response))")
            DispatchQueue.main.async {
                self.sendingErorReport();
            }
        }
        
        
        
        do {
            let json = try JSONSerialization.jsonObject(with: data, options:JSONSerialization.ReadingOptions()) as (AnyObject)

            collectionData  = json as AnyObject
            if(signalName.compare("HttpLoginPostMetod") == .orderedSame){
            collection = collectionData as! NSDictionary
            let defaults = UserDefaults.standard;
            defaults .set(collection["sessionId"], forKey: "sessionId")
            DispatchQueue.main.async {
            self.startCallingApi();
            }
            }
            else if(signalName.compare("HttpPostMetod") == .orderedSame){
                DispatchQueue.main.async {
                self.startFinalData();
                }
            }
            
        } catch {
            print("json error: \(error)")
            DispatchQueue.main.async {
                self.sendingserverErrorReport();
            }
            
            
        }
    }
    
    task.resume()
  
  //}
    
}

func callingHttpPostMethod (params:String,apiname : String ,signalName: String){

let defaults = UserDefaults.standard;

let urlString = BASE_DOMAIN + apiname

print("url %@",urlString);

print("params %@",params);

//queue.async {

var request = URLRequest(url: URL(string: urlString)!)

request.httpMethod = "POST"

let postString = params;

request.httpBody = postString.data(using: .utf8)

if defaults.object(forKey: "authKey") == nil{

request.addValue("", forHTTPHeaderField: "authKey")

request.addValue(API_USER_NAME, forHTTPHeaderField: "apiKey")

request.addValue(API_KEY, forHTTPHeaderField: "apiPassword")

}

else{

request.addValue(defaults.object(forKey: "authKey") as! String, forHTTPHeaderField: "authKey")

request.addValue(API_USER_NAME, forHTTPHeaderField: "apiKey")

request.addValue(API_KEY, forHTTPHeaderField: "apiPassword")

}

task = URLSession.shared.dataTask(with: request) { data, response, error in

guard let data = data, error == nil else { // check for fundamental networking error

print("error=\(String(describing: error))", "aaa",error)

if let error = error as NSError?, error.domain == NSURLErrorDomain && error.code == NSURLErrorCancelled {

}

else{

DispatchQueue.main.async {

self.sendingErorReport();

}

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 = \(String(describing: response))")

DispatchQueue.main.async {

self.sendingErorReport();

}

do {

let json = try JSONSerialization.jsonObject(with: data, options:JSONSerialization.ReadingOptions()) as (AnyObject)

collectionData = json as AnyObject

if(signalName.compare("HttpLoginPostMetod") == .orderedSame){

collection = collectionData as! NSDictionary

let defaults = UserDefaults.standard;

defaults .set(collection["sessionId"], forKey: "sessionId")

DispatchQueue.main.async {

self.startCallingApi();

}

else if(signalName.compare("HttpPostMetod") == .orderedSame){

DispatchQueue.main.async {

self.startFinalData();

}

} catch {

print("json error: \(error)")

DispatchQueue.main.async {

self.sendingserverErrorReport();

}

task.resume()

//}

}

Note:

a: here task is a global variable.

b: if let error = error as NSError?, error.domain == NSURLErrorDomain && error.code == NSURLErrorCancelled { }

This one detects when we cancel the previous task.

If this will execute we will nothing to do otherwise we are maintaining the server error response.

3: in every view controller we are doing this:

override func viewWillDisappear(_ animated: Bool) {
        SVProgressHUD.dismiss()
        globalObjectAddReview.cancelNetworkRequest()
        
    }

override func viewWillDisappear(_ animated: Bool) {

SVProgressHUD.dismiss()

globalObjectAddReview.cancelNetworkRequest()

}

4: define this method in the global class where we have written the network request.

func cancelNetworkRequest(){
    print("cancelled")
    task.cancel()
}

func cancelNetworkRequest(){

print("cancelled")

task.cancel()

}

5: Now this will cancel the previous request and load the current request.

kunal prasad 23 September 2017

. . .

Drop the current HTTP request in URLSession using swift 3

Drop Request

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