I have a log in page that collects a username and password. On submit, Its sends to the database to retrieve our servers access key. I do this through an asynchronous JSON POST using session.dataTask. When I retrieve the JSON Object I parse the key out of it. I want to pass it to the next page, retrieve a firebase token and then send both pieces of data back to the server for DB storage. I have created a "prepare for segue" function that collects the variable and passes it to a variable on the next page. I believe I am not setting up the sequence of events correctly or that the data isn't making it out of the Async container. Can someone have a look at these two files and see where I am getting it wrong?
Here is the first page I want to segue away from after making the REST web service call...
loginVC.swift:
import UIKit
class LoginVC: UIViewController {
@IBOutlet weak var username: UITextField!
@IBOutlet weak var password: UITextField!
@IBOutlet weak var validationBox: UITextView!
@IBAction func logInAction(_ sender: UIButton) {
guard let user = username.text, !user.isEmpty else {
validationBox.text = "Please enter valid credentials"
return
}
guard let pass = password.text, !pass.isEmpty else {
validationBox.text = "Please enter valid credentials"
return
}
let params = ["sUser": username.text!, "sPass": password.text!]
let url = URL(string: "restWebServiceURL")!
let session = URLSession.shared
var request = URLRequest(url: url)
request.httpMethod = "POST"
do {
request.httpBody = try JSONSerialization.data(withJSONObject: params, options: .prettyPrinted)
} catch let error {
print(error.localizedDescription)
}
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")
let task = session.dataTask(with: request as URLRequest, completionHandler: { data, response, error in
guard error == nil else { return }
guard let data = data else { return }
do {
if let parsedJSON = try JSONSerialization.jsonObject(with: data, options: .mutableContainers) as? [String: Any] {
let parsedData = parsedJSON["d"] as! [String:Any]
let key = parsedData["key"] as! String
DispatchQueue.main.async {
print(key)
self.performSegue(withIdentifier: "FirebaseVC", sender: key)
}
}
} catch let error {
print(error.localizedDescription)
}
})
task.resume()
}
func sayHello() {
print("Hello!")
}
func sayGoodbye() {
print("Goodbye!")
}
override func viewDidLoad() {
super.viewDidLoad()
validationBox.text = "Ready..."
func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let FirebaseInit = segue.destination as? FirebaseVC {
if let sKey = sender as? String {
print("prepare - " + sKey)
FirebaseInit.sessionKey = sKey
}
}
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
Here is the page I want to go to to receive the data access key ...
FirebaseVC.swift:
import UIKit
class FirebaseVC: UIViewController {
private var _sessionKey = String()
var sessionKey : String {
get { return _sessionKey }
set { _sessionKey = newValue }
}
@IBOutlet weak var sessionKeyTestBox: UITextView!
override func viewDidLoad() {
super.viewDidLoad()
print(_sessionKey)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
Feel free to suggest a better way to pass the data to the next page. Thanks...
It turns out I was correct in my assumption the the chain of events was off. Following the model suggested by @achrefGassoumi, I moved the datatask to a Singleton Service here:
import Foundation
struct CallWebService {
static let sharedInstance = CallWebService()
func logInToCaduceus(u: String, p: String, completion: @escaping (_ sKey: String) -> ()) {
let params = ["sUser": u, "sPass": p]
let url = URL(string: "https://telemed.caduceususa.com/ws/telemed.asmx/telemedLogin")!
let session = URLSession.shared
var request = URLRequest(url: url)
request.httpMethod = "POST"
do {
request.httpBody = try JSONSerialization.data(withJSONObject: params, options: .prettyPrinted)
} catch let error {
print(error.localizedDescription)
}
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")
let task = session.dataTask(with: request as URLRequest, completionHandler: { data, response, error in
guard error == nil else { return }
guard let data = data else { return }
do {
if let parsedJSON = try JSONSerialization.jsonObject(with: data, options: .mutableContainers) as? [String: Any] {
let parsedData = parsedJSON["d"] as! [String:Any]
let key = parsedData["key"] as! String
DispatchQueue.main.async {
completion(key)
}
}
} catch let error {
print(error.localizedDescription)
}
})
task.resume()
}
}
Then my two controllers look like this:
LoginVC
import UIKit
class LoginVC: UIViewController {
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if (segue.destination.isKind(of: FirebaseVC.self)) {
let vc = segue.destination as! FirebaseVC
if let sKey = sender as? String {
vc.sessionKey = sKey
}
}
}
@IBOutlet weak var username: UITextField!
@IBOutlet weak var password: UITextField!
@IBOutlet weak var validationBox: UITextView!
@IBAction func logInAction(_ sender: UIButton) {
guard let user = username.text, !user.isEmpty else {
validationBox.text = "Please enter valid credentials"
return
}
guard let pass = password.text, !pass.isEmpty else {
validationBox.text = "Please enter valid credentials"
return
}
CallWebService.sharedInstance.logInToCaduceus(u: username.text!, p: password.text!, completion: {(sessionKey: String) -> Void in
print(sessionKey)
self.performSegue(withIdentifier: "FirebaseVC", sender: sessionKey)
}
)
}
override func viewDidLoad() {
super.viewDidLoad()
//validationBox.textAlignment = .center
validationBox.text = "Ready..."
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
AND THE receiving FirebaseVC
import UIKit
class FirebaseVC: UIViewController {
private var _sessionKey = String()
var sessionKey : String {
get { return _sessionKey }
set { _sessionKey = newValue }
}
@IBOutlet weak var sessionKeyTestBox: UITextView!
override func viewDidLoad() {
super.viewDidLoad()
sessionKeyTestBox.text = _sessionKey
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
}
Excuse my (non-swift) Javascript terminology but essentially I moved the data call into a service and then place a callback method in the service with the completion method to ensure the the performSegue doesn't fire until the data has been received and parsed out. So when i submit the log in form data to the server the segue doesn't fire until that async call has been completed.