Signing Out of Firebase in Swift - swift

Question

I am attempting to sign out of the Firebase API, but I can't seem to figure out how to handle any errors that may occur.
The Firebase pod provides a method for signing out:
FIRAuth.auth()?.signOut()
It is marked with throws, so I have wrapped it in a do/try/catch block in a method to test the signing out process:
do {
try FIRAuth.auth()?.signOut()
} catch (let error) {
print((error as NSError).code)
}
I see that the signOut method is marked with throws in the Firebase pod, but I don't see how it can handle any errors asynchronously. I have tried entering Airplane Mode, which triggers a network error in my code everywhere else that a network request takes place, but with the signOut method, that error isn't caught because I have no completion handler to execute from. All of the other authentication methods from the Firebase pods have a completion handler, in which I am able to handle errors.
Here is the documentation for the signOut method from the Firebase pod:
/** #fn signOut:
#brief Signs out the current user.
#param error Optionally; if an error occurs, upon return contains an NSError object that
describes the problem; is nil otherwise.
#return #YES when the sign out request was successful. #NO otherwise.
#remarks Possible error codes:
- #c FIRAuthErrorCodeKeychainError Indicates an error occurred when accessing the keychain.
The #c NSLocalizedFailureReasonErrorKey field in the #c NSError.userInfo dictionary
will contain more information about the error encountered.
*/
open func signOut() throws
Do you have any suggestions for an appropriate way to handle the signing out of a user when I don't have a completion handler that allows me to check for an error?

Answer 1

You can catch the error like this
do
{
try Auth.auth().signOut()
}
catch let error as NSError
{
print(error.localizedDescription)
}

Answer 2

Edited from Milli's answer to add sending user back to initial page of the app.
// log out
func logout(){
do
{
try Auth.auth().signOut()
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let IntroVC = storyboard.instantiateViewController(withIdentifier: "IntroVC") as! introVC
let appDelegate = UIApplication.shared.delegate as! AppDelegate
appDelegate.window?.rootViewController = IntroVC
}
catch let error as NSError
{
print(error.localizedDescription)
}
}

Answer 3

An error is highly unlikely to occur but it's never good to assume anything. By the sound of the documentation, it wipes out your keychain which is the only way you'd be able to log back into your firebase application. From trying logging out of my own firebase app I was surprise that 0 errors occured. Here is the original code.
#IBAction func logOutTapped(_ sender: Any) {
let firebaseAuth = FIRAuth.auth()
do {
try firebaseAuth?.signOut()
} catch let signOutError as NSError {
print ("Error signing out: %#", signOutError)
}
if Utility.hasFacebook {
let login = FBSDKLoginManager()
login.logOut()
}
if Utility.hasTwitter {
Twitter.sharedInstance().sessionStore.logOutUserID((Twitter.sharedInstance().sessionStore.session()?.userID)!)
}
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let initialViewController = storyboard.instantiateViewController(withIdentifier: "LoginVC")
self.present(initialViewController, animated: false)
}
Anyways if you really want a completion handler then here's something I tossed up quickly
func logOut(completion:#escaping(_ errorOccured: Bool) -> Void) {
let firebaseAuth = FIRAuth.auth()
do {
try firebaseAuth?.signOut()
} catch let signOutError as NSError {
completion(true)
}
completion(false)
}