Twitter / Fabric login button not behaving as expected

Question

I have a very simple iOS project where I'm using Twitter/Fabric login button for user login to my app.

I've managed to get the Fabric login button working. When the user clicks on the Twitter login button they are automatically authenticated (that's if they are logged into the Twitter app) otherwise the user is presented with a Twitter login screen.

I'm not sure why the user is automatically authenticated when they are logged into the Twitter app on their phone.

Is there a way to use the Twitter/Fabic API to open the Twitter app and ask for permission to grant access to my app similar to Facebook login even if the user is logged into the Twitter App.

This is what my AppDelegate looks like:

Twitter.sharedInstance().start(withConsumerKey: "someKey", consumerSecret: "someSecret")
Fabric.with([Twitter.self])

This is what my ViewController looks like:

@IBOutlet private weak var twitterLoginButton: TWTRLogInButton!

// and 
twitterLoginButton.logInCompletion = {(session, error) in
        if error != nil {
            print("ERROR: \(error)")
        } else {
            if let unwrappedSession = session {
                print(unwrappedSession.userName)
            }
        }
}

Twitter.sharedInstance().logIn { (session, error) in
        if let unwrappedSession = session {
            print("Signed in as: \(unwrappedSession.userName)")
        } else {
            print("ERROR: \(error)")
        }
}

Answer 1

Fabric documentation says that the first default for login is to go through the Twitter app (that may be why your user is automatically authenticated if they're already logged in the app), otherwise it will go through the webAuth login flow.

"To force the log in flow to use the web OAuth flow pass the TWTRLoginMethodWebBased method to the relevant log in methods."

// If using the TWTRLoginButton
let logInButton = TWTRLogInButton() { session, error in
}
logInButton.loginMethods = [.webBased]

So if you want to force the user to go through the web flow, try adding to your code: twitterLoginButton.loginMethods = [.webBased]