Doesn't call Facebook loginButton didCompleteWithResult - ios

Question

I followed the tutorial here to integrate Facebook login on my application. I can login successfully with that button, but it doesn't call my method didCompleteWithResult upon login to fetch user details. This is my code.
import UIKit
class LoginViewController: UIViewController, FBSDKLoginButtonDelegate {
#IBOutlet weak var loginBtn: FBSDKLoginButton!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func configureFacebook()
{
loginBtn.readPermissions = ["public_profile", "email", "user_friends"];
loginBtn.delegate = self
}
func loginButton(loginButton: FBSDKLoginButton!, didCompleteWithResult result: FBSDKLoginManagerLoginResult!, error: NSError!){
FBSDKGraphRequest.init(graphPath: "me", parameters: ["fields":"first_name, last_name, picture.type(large)"]).startWithCompletionHandler { (connection, result, error) -> Void in
let strFirstName: String = (result.objectForKey("first_name") as? String)!
let strLastName: String = (result.objectForKey("last_name") as? String)!
let strPictureURL: String = (result.objectForKey("picture")?.objectForKey("data")?.objectForKey("url") as? String)!
print("Welcome, \(strFirstName) \(strLastName)")
//self.profilePic.image = UIImage(data: NSData(contentsOfURL: NSURL(string: strPictureURL)!)!)
}
}
func loginButtonDidLogOut(loginButton: FBSDKLoginButton!)
{
}
}

Answer 1

Option-1
I dont know where you add this method in here I submit answer in dynamically , customize your self..
override func viewDidLoad() {
super.viewDidLoad()
configureFacebook() // if you want here add here or else if you want to load the facebook details in Button action add there
// Do any additional setup after loading the view.
}
func configureFacebook()
{
loginBtn.readPermissions = ["public_profile", "email", "user_friends"];
loginBtn.delegate = self
}
option-2
if you add the delegate in directly in your viewcontroller do like for example