Data persistence in GraphRequest with FBSDK - ios

Question

Good afternoon community,
I'm trying to get the data from graphrequest and be able to pass the data to another viewController, but apparently it doesn't get saved in a variable, outside of making the query, the data is removed, it doesn't get saved in a variable.
Have any of you had this problem or something like that?
I leave my code below of my first viewController
import UIKit
import FBSDKLoginKit
class ViewController: UIViewController,FBSDKLoginButtonDelegate {
#IBOutlet var test: UILabel!
var comprobacion = "";
override func viewDidLoad() {
super.viewDidLoad()
if let token = FBSDKAccessToken.current(), !token.isExpired {
let loginButton = FBSDKLoginButton()
loginButton.center = view.center
loginButton.layoutIfNeeded()
loginButton.delegate = self
view.addSubview(loginButton)
loginButton.awakeFromNib()
loginButton.readPermissions = ["public_profile", "email"]
}else{
let loginButton = FBSDKLoginButton()
loginButton.center = view.center
loginButton.delegate = self
view.addSubview(loginButton)
loginButton.layoutIfNeeded()
loginButton.awakeFromNib()
loginButton.readPermissions = ["public_profile", "email"]
}
}
func loginButton(_ loginButton: FBSDKLoginButton!, didCompleteWith result: FBSDKLoginManagerLoginResult!, error: Error!) {
let resultado = result?.token?.tokenString
let request = FBSDKLoginKit.FBSDKGraphRequest(graphPath: "me", parameters: ["fields":"email,name"], tokenString: resultado, version: nil, httpMethod: "get")
request?.start(completionHandler: { connection , result, error in
let datos: [String:AnyObject] = result as! [String:AnyObject];
self.comprobacion = (datos["email"] as! NSString) as String;
print("campos \(String(describing: result) )")
self.test.text = self.comprobacion
})
performSegue(withIdentifier: "second", sender: self)
let storyBoard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
let newViewController = storyBoard.instantiateViewController(withIdentifier: "SecondController") as! SecondController
self.present(newViewController, animated: true, completion: nil)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
let destino = segue.destination as! SecondController
destino.recibir = comprobacion;
}
func loginButtonDidLogOut(_ loginButton: FBSDKLoginButton!) {
print("GoodBye... Hommi")
}
}
I leave my code below of my second viewController
import UIKit
class SecondController: UIViewController {
#IBOutlet var Email: UILabel!
var recibir: String!
override func viewDidLoad() {
super.viewDidLoad()
print("recibir \(String(describing: recibir))")
Email.text = String(recibir)
}
}
I realized that the email is not saved in my variable, since it is outside the clousure request.start if I print the variable it is empty.
some help?

Answer 1

Re-arrange code to
func loginButton(_ loginButton: FBSDKLoginButton!, didCompleteWith result: FBSDKLoginManagerLoginResult!, error: Error!) {
let resultado = result?.token?.tokenString
let request = FBSDKLoginKit.FBSDKGraphRequest(graphPath: "me", parameters: ["fields":"email,name"], tokenString: resultado, version: nil, httpMethod: "get")
request?.start(completionHandler: { connection , result, error in
let datos: [String:AnyObject] = result as! [String:AnyObject];
self.comprobacion = (datos["email"] as! NSString) as String;
print("campos \(String(describing: result) )")
self.test.text = self.comprobacion
DispatchQueue.main.async {
self.performSegue(withIdentifier: "second", sender: self)
}
})
}
Tips
1- Code inside request?.start(completionHandler runs asynchnoulsy after the segue so the segue occurs while your var is still nil
2- Don't instantiate a vc and present it when you already use a segue