Retrieve Facebook user ID in Swift - ios

Question

I have a helper function that is grabbing the picture from a specific URL:
func getProfilePicture(fid: String) -> UIImage? {
if (fid != "") {
var imageURLString = "http://graph.facebook.com/" + fid + "/picture?type=large"
var imageURL = NSURL(string: imageURLString)
var imageData = NSData(contentsOfURL: imageURL!)
var image = UIImage(data: imageData!)
return image
}
return nil
}
I proceed to call getProfilePicture() with the user's Facebook ID, and store the output into a UIImageView. My question is, how can I find a Facebook user's ID? Do I request a connection through Facebook? It would be helpful if some code is provided here.
Thank you for your help.

Answer 1

If they are already successfully logged into your app:
FBSDKAccessToken.current().userID

Answer 2

What worked for me:
Use FBSDKLoginButtonDelegate
Implement func loginButtonWillLogin
Add notification to onProfileUpdated
In onProfileUpdated func proceed to get your Profile info
After onProfileUpdated is called, you can use your FBSDKProfile in any Controller
And now, some Swift 3 code...
import UIKit
import FBSDKLoginKit
class ViewController: UIViewController, FBSDKLoginButtonDelegate {
override func viewDidLoad() {
super.viewDidLoad()
// Facebook login integration
let logBtn = FBSDKLoginButton()
logBtn.center = self.view.center
self.view .addSubview(logBtn)
logBtn.delegate = self
}
func loginButtonWillLogin(_ loginButton: FBSDKLoginButton!) -> Bool {
print("will Log In")
FBSDKProfile.enableUpdates(onAccessTokenChange: true)
NotificationCenter.default.addObserver(self, selector: #selector(onProfileUpdated(notification:)), name:NSNotification.Name.FBSDKProfileDidChange, object: nil)
return true
}
func onProfileUpdated(notification: NSNotification)
{
print("profile updated")
print("\(FBSDKProfile.current().userID!)")
print("\(FBSDKProfile.current().firstName!)")
}
}