Code extraction on Afnetworking post request - ios

Question

I am trying to extract a post request so it can be re-used and keep my code as DRY as possible bu I'm struggling a little. I started off with:
func createAccount() {
let manager = AFHTTPSessionManager()
let dob = self.dobTextField.text!.components(separatedBy: "/")
let URL = "https://splitterstripeservertest.herokuapp.com/account"
let params = [
"first_name": firstNameTextField.text!.trim(),
"last_name": lastNameTextField.text!.trim(),
"line1": addressLine1TextField.text!.trim(),
"city": cityTextField.text!.trim(),
"postal_code": postCodeTextField.text!.trim(),
"email": emailTextField.text!.trim(),
"day": UInt(dob[0])! as UInt,
"month": UInt(dob[1])! as UInt,
"year": UInt(dob[2])! as UInt] as [String : Any]
manager.requestSerializer = AFHTTPRequestSerializer()
manager.responseSerializer = AFHTTPResponseSerializer()
manager.post(URL, parameters: params, progress: nil, success: {(_ task: URLSessionDataTask, _ responseObject: Any) -> Void in
do {
let response = try JSONSerialization.jsonObject(with: responseObject as! Data, options: .mutableContainers) as? [String: Any]
self.stripeAccountID = response?["id"] as! String
self.stopAnimating()
self.goToFinalStage()
} catch {
print("Serialising new account json object went wrong.")
self.stopAnimating()
}
}, failure: { (operation, error) -> Void in
self.handleError(error as NSError)
self.stopAnimating()
})
}
and have it down to:
func createAccount() {
let request = HttpRequest()
let response = request.post(params: setParams(), URLExtension: "account")
if (response != nil) {
successfulRequest(response: response!)
} else {
failedRequest(response: response!)
}
}
func successfulRequest(response: AnyObject) {
self.stripeAccountID = response["id"] as! String
createMainBillSplitter()
self.stopAnimating()
performSegue(withIdentifier: "segueToFinalRegistrationViewController", sender: self)
}
func failedRequest(response: AnyObject) {
self.stopAnimating()
self.handleError(response["failed"] as! NSError)
}
where HTTPRequest is:
class HttpRequest {
let manager = AFHTTPSessionManager()
let baseURL = "https://splitterstripeservertest.herokuapp.com/account"
func post(params: [String: Any], URLExtension: String) -> AnyObject? {
let URL = baseURL + URLExtension
var response = [String: Any]()
manager.requestSerializer = AFHTTPRequestSerializer()
manager.responseSerializer = AFHTTPResponseSerializer()
manager.post(URL, parameters: params, progress: nil, success: {(_ task: URLSessionDataTask, _ responseObject: Any) -> Void in
do {
response = try JSONSerialization.jsonObject(with: responseObject as! Data, options: .mutableContainers) as! [String: Any]
} catch {
print("Serialising new account json object went wrong.")
}
}, failure: { (operation, error) -> Void in
response = ["failed": error]
})
return response as AnyObject?
}
func handleError(_ error: NSError) -> UIAlertController {
let alert = UIAlertController(title: "Please Try Again", message: error.localizedDescription, preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "OK", style: .cancel, handler: nil))
return alert
}
}
But, I'm getting errors because the response is nil, which I'm sure is because there aren't completion handlers. I just don't understand enough how to implement them in this situation, so would really appreciate a push in the right direction. Thanks in advance!

Answer 1

You are getting confused with sync vs async operations.
The manager.post function will create your http request and will call the success closure when it is done. But since that function is implemented as an async operation, your code will not stop while that http request is being executed. So, your code will continue to be executed, and in your case, the very next line is you returning the response that is basically your empty array of Strings.
func post(params: [String: Any], URLExtension: String) -> AnyObject? {
let URL = baseURL + URLExtension
var response = [String: Any]()
manager.requestSerializer = AFHTTPRequestSerializer()
manager.responseSerializer = AFHTTPResponseSerializer()
manager.post(URL, parameters: params, progress: nil, success: {(_ task: URLSessionDataTask, _ responseObject: Any) -> Void in
// this closure is executed only when the request is completed
do {
response = try JSONSerialization.jsonObject(with: responseObject as! Data, options: .mutableContainers) as! [String: Any]
} catch {
print("Serialising new account json object went wrong.")
}
}, failure: { (operation, error) -> Void in
response = ["failed": error]
})
return response as AnyObject? // <<-- this line is executed right after the manager.post line above, but the success closure was not called yet because the request is still going on.
}
So, what you need to do is to not return the response right after the manager.post was called, but return it from inside the success closure. But you cannot simply use a return response statement. You need to pass the response as a parameter to a callback closure that you would pass to your request.post function.
Something like this:
func createAccount() {
let request = HttpRequest()
let response = request.post(params: setParams(),
URLExtension: "account",
success: {response in
// enter here the code to be executed when request is completed.
successfulRequest(response: response)
},
fail: {response in
failedRequest(response: response)
},)
}
and your class HttpRequest post function would be:
func post(params: [String: Any], URLExtension: String, success:([String: Any] -> Void), fail:([String: Any] -> Void)) -> AnyObject? {
let URL = baseURL + URLExtension
manager.requestSerializer = AFHTTPRequestSerializer()
manager.responseSerializer = AFHTTPResponseSerializer()
manager.post(URL, parameters: params, progress: nil, success: {(_ task: URLSessionDataTask, _ responseObject: Any) -> Void in
do {
response = try JSONSerialization.jsonObject(with: responseObject as! Data, options: .mutableContainers) as! [String: Any]
success(response)
} catch {
print("Serialising new account json object went wrong.")
}
}, failure: { (operation, error) -> Void in
response = ["failed": error]
fail(response)
})
}
PS: your code is assuming that it will always be able to decode the JSON response. Although you are using do / catch, if for some reason the JSON decoding fails, no response is being send back to your calling function. So, the app will just be stuck. I suggest you calling the fail() callback inside your catch block.