How to Log out from Facebook or revoke login using Parse and Swift

Question

I'm trying to completely log my user out of my app. When using

PFUser.logout()

I successfully log the user out of Parse. But when I come back in the app and click on the login button, I'm redirected to the Facebook screen saying :"You have already authorized [name of the app]" So I can never login again with another account, except if I reset the simulator.

I also tried to logout using

PFFacebookUtils.facebookLoginManager().logOut()

But it doesn't work either... Hope you can help me find a solution to this ! I'm using the latest Facebook and Parse SDK

Update:

Actually using PFUser.logout() and the last versions of Parse and the Facebook iOS SDK version >= 4.4.0 will do the job.

Do not use PFFacebookUtils.facebookLoginManager().logOut() or FBSDKLoginManager().logOut(), because it will only log the user out from Facebook but not from the Parse back-end. Which means that it will not delete the revocable session on the Parse back-end.

Answer 1

Actually there is a difference between Revoking Login (letting people completely de-authorizing an app, or revoking login) and Logging out an user from his/her Facebook account:

Revoking Login

(you can check the Facebook documentation)

You can also let people completely de-authorize an app, or revoke login, by making a call to this Graph API endpoint:

DELETE /{user-id}/permissions

This request must be made with a valid user access token or an app access token for the current app. If the request is successful, your app receives a response of true. If the call is successful, any user access token for the person will be invalidated and they will have to log in again. Because you're de-authorizing your app, they will also have to grant access to your app as if they were logging in for the first time.

let facebookRequest: FBSDKGraphRequest! = FBSDKGraphRequest(graphPath: "/me/permissions", parameters: nil, HTTPMethod: "DELETE")

facebookRequest.startWithCompletionHandler { (connection: FBSDKGraphRequestConnection!, result: AnyObject!, error: NSError!) -> Void in

                if(error == nil && result != nil){
                    println("Permission successfully revoked. This app will no longer post to Facebook on your behalf.")
                    println("result = \(result)")
                } else {
                    if let error: NSError = error {
                        if let errorString = error.userInfo?["error"] as? String {
                            println("errorString variable equals: \(errorString)")
                        }
                    } else {
                        println("No value for error key")
                    }
                }
}

Logging out an user form his/her Facebook account

If you have used Parse and the Facebook iOS SDK version >= 4.4.0 to sign up or log in a user via Facebook, and you do not want to de-authorize an app, or revoke login, but just want to log out the user from Facebook, then please use instead:

PFUser.logOut()

It will log out the user, delete the session on the Parse back-end side (do not forget to enable Parse revocable session via your Parse app settings), plus it will also delete the Facebook session written on the user device's disk.

I hope this answer will help you guys.

Answer 2

Source: Logout from facebook in iOS app

- (void)logout:(id<FBSessionDelegate>)delegate {

  _sessionDelegate = delegate;

  NSMutableDictionary * params = [[NSMutableDictionary alloc] init];
  [self requestWithMethodName:@"auth.expireSession"
                    andParams:params andHttpMethod:@"GET"
                  andDelegate:nil];

  [params release];
  [_accessToken release];
  _accessToken = nil;
  [_expirationDate release];
  _expirationDate = nil;

  NSHTTPCookieStorage* cookies = [NSHTTPCookieStorage sharedHTTPCookieStorage];
  NSArray* facebookCookies = [cookies cookiesForURL:
    [NSURL URLWithString:@"https://m.facebook.com"]];

  for (NSHTTPCookie* cookie in facebookCookies) {
    [cookies deleteCookie:cookie];
  }

  if ([self.sessionDelegate respondsToSelector:@selector(fbDidLogout)]) {
    [_sessionDelegate fbDidLogout];
  }
}

Answer 3

I just implemented this. Call this function from any viewController in the application and it will logout from facebook. Worked like a charm for me. I hope it helps you.

-(void) logout
{
    FBSDKLoginManager *login = [[FBSDKLoginManager alloc] init];

    if ( [FBSDKAccessToken currentAccessToken] ){
        [login logOut];
    }
}