How to logout user using Facebook authentication using Swift and iOS?

问题

I\'ve tried searching around but I can\'t find the answer to my question.

I\'m playing around with this application from github: https://github.com/Yalantis/Koloda/tree/master/Example

I\'m using it because I\'m doing a project which will use the tile based swiping from this application.

I\'m also using firebase. So far, I can add users to my database, so the app and firebase are connected.

I also want users to register/login using facebook.

I have connected my app to facebook and a user can come in and successfully login using facebook authentication.

The problem I am having is logging out.

When I click on the logout button, I want the user to be completely logged out. So there is a logout method that comes with the facebook SDK called logout. Here are the relevant parts of my code.

import FBSDKLoginKit
@IBAction func handleLogout(sender: AnyObject) {

    facebookLogin.logOut()
    print(\"loggedout\")
    }

So when I click on logout and then click on login again I get this page:

http://imgur.com/owi3zZn

I do not want the user to stay authorized after they have clicked on the logout button. How do I make it so that when I click on the logout button, the user is completely logged out from Facebook and then when they click on the login button they have to re-enter their username/password?

I\'ve tried looking around the webz but can\'t find a solution to my problem, although I\'m sure it\'s something pretty simple, I hope!

Thank you for your help and sorry if the formatting is poor.

回答1:

When you call the logOut, the user is logged out of your app. As far as logging them out of Facebook, I don't think you can do that, nor would Facebook allow it. The first time a user authorizes you app through Facebook, Facebook adds your app to the list of apps that they are authorized with (they can access that page through Facebook.com). When they logOut and logIn again, they will see the page that you posted a picture of because they already authorized it. The only way for them to reauthorize themselves is to delete the app from their Facebook app page and log in to your app again.

回答2:

If you to make user log out from the app itself programmatically you can check the following code

let loginView : FBSDKLoginManager = FBSDKLoginManager()
loginView.loginBehavior = FBSDKLoginBehavior.Web

This will open the facebook login popup in your app in which user can login in your app

And for the logout, you can call

let manager = FBSDKLoginManager()
manager.logOut()

This will log out user from the facebook in the app, after this if you call login method of SDK you will see the login popup again

If you want to clear the profile and token also call the below code with logout

 FBSDKAccessToken.setCurrentAccessToken(nil)
 FBSDKProfile.setCurrentProfile(nil)

回答3:

The way the current Facebook SDK handles this seems like a security vulnerability to me. If I borrow a friends iPad and login to an app with Facebook when I logout I should be completely logged out of the app and the SFSafariViewController it used to authenticate me. Whereas right now it still remembers me in the SFSafariViewController using cookies.

To properly log the user out both from the Facebook SDK and SFSafariViewController I do the following:

    let fbLoginManager = FBSDKLoginManager()
    fbLoginManager.logOut()
    let cookies = HTTPCookieStorage.shared
    let facebookCookies = cookies.cookies(for: URL(string: "https://facebook.com/")!)
    for cookie in facebookCookies! {
        cookies.deleteCookie(cookie )
    }

I really dislike this solution but it's the best I've been able to come up with.

回答4:

User Dan L has the correct answer, in one of my comments he wrote:

Oh, I see what you mean. If you go into the safari app, you can go Facebook.com and logout of your account, login to a different account, and go back into your app. The safari extension the pops up when you call the Facebook login should show the new user that logged in!

This is exactly what I needed. Thank you Dan L.