@brief The name of the NSNotificationCenter notification which is posted when the auth state
changes (for example, a new token has been produced, a user signs in or signs out). The
object parameter of the notification is the sender Auth instance.
@brief Errors with one of the following three codes:
- AuthErrorCodeAccountExistsWithDifferentCredential
- AuthErrorCodeCredentialAlreadyInUse
- AuthErrorCodeEmailAlreadyInUse
may contain an NSError.userInfo dictionary object which contains this key. The value
associated with this key is an NSString of the email address of the account that already
exists.
@brief The key used to read the updated Auth credential from the userInfo dictionary of the
NSError object returned. This is the updated auth credential the developer should use for
recovery if applicable.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-27 UTC."],[],[],null,["# FirebaseAuth Framework Reference\n\nConstants\n=========\n\nThe following constants are available globally.\n- `\n ``\n ``\n `\n\n ### [AuthStateDidChange](#/c:@FIRAuthStateDidChangeNotification)\n\n `\n ` \n @brief The name of the `NSNotificationCenter` notification which is posted when the auth state\n changes (for example, a new token has been produced, a user signs in or signs out). The\n object parameter of the notification is the sender [Auth](/docs/reference/swift/firebaseauth/api/reference/Classes/Auth) instance. \n\n #### Declaration\n\n Swift \n\n static let AuthStateDidChange: NSNotification.Name\n\n- `\n ``\n ``\n `\n\n ### [AuthErrorDomain](#/c:@FIRAuthErrorDomain)\n\n `\n ` \n @brief The Firebase Auth error domain. \n\n #### Declaration\n\n Swift \n\n let AuthErrorDomain: String\n\n- `\n ``\n ``\n `\n\n ### [AuthErrorUserInfoNameKey](#/c:@FIRAuthErrorUserInfoNameKey)\n\n `\n ` \n @brief The name of the key for the error short string of an error code. \n\n #### Declaration\n\n Swift \n\n let AuthErrorUserInfoNameKey: String\n\n- `\n ``\n ``\n `\n\n ### [AuthErrorUserInfoEmailKey](#/c:@FIRAuthErrorUserInfoEmailKey)\n\n `\n ` \n @brief Errors with one of the following three codes:\n - `AuthErrorCodeAccountExistsWithDifferentCredential`\n - `AuthErrorCodeCredentialAlreadyInUse`\n - `AuthErrorCodeEmailAlreadyInUse`\n may contain an `NSError.userInfo` dictionary object which contains this key. The value\n associated with this key is an NSString of the email address of the account that already\n exists. \n\n #### Declaration\n\n Swift \n\n let AuthErrorUserInfoEmailKey: String\n\n- `\n ``\n ``\n `\n\n ### [AuthErrorUserInfoUpdatedCredentialKey](#/c:@FIRAuthErrorUserInfoUpdatedCredentialKey)\n\n `\n ` \n @brief The key used to read the updated Auth credential from the userInfo dictionary of the\n NSError object returned. This is the updated auth credential the developer should use for\n recovery if applicable. \n\n #### Declaration\n\n Swift \n\n let AuthErrorUserInfoUpdatedCredentialKey: String\n\n- `\n ``\n ``\n `\n\n ### [AuthErrorUserInfoMultiFactorResolverKey](#/c:@FIRAuthErrorUserInfoMultiFactorResolverKey)\n\n `\n ` \n @brief The key used to read the MFA resolver from the userInfo dictionary of the NSError object\n returned when 2FA is required for sign-incompletion. \n\n #### Declaration\n\n Swift \n\n let AuthErrorUserInfoMultiFactorResolverKey: String\n\n- `\n ``\n ``\n `\n\n ### [EmailAuthProviderID](#/c:@FIREmailAuthProviderID)\n\n `\n ` \n @brief A string constant identifying the email \\& password identity provider. \n\n #### Declaration\n\n Swift \n\n let EmailAuthProviderID: String\n\n- `\n ``\n ``\n `\n\n ### [EmailLinkAuthSignInMethod](#/c:@FIREmailLinkAuthSignInMethod)\n\n `\n ` \n @brief A string constant identifying the email-link sign-in method. \n\n #### Declaration\n\n Swift \n\n let EmailLinkAuthSignInMethod: String\n\n- `\n ``\n ``\n `\n\n ### [EmailPasswordAuthSignInMethod](#/c:@FIREmailPasswordAuthSignInMethod)\n\n `\n ` \n @brief A string constant identifying the email \\& password sign-in method. \n\n #### Declaration\n\n Swift \n\n let EmailPasswordAuthSignInMethod: String\n\n- `\n ``\n ``\n `\n\n ### [FacebookAuthProviderID](#/c:@FIRFacebookAuthProviderID)\n\n `\n ` \n @brief A string constant identifying the Facebook identity provider. \n\n #### Declaration\n\n Swift \n\n let FacebookAuthProviderID: String\n\n- `\n ``\n ``\n `\n\n ### [FacebookAuthSignInMethod](#/c:@FIRFacebookAuthSignInMethod)\n\n `\n ` \n @brief A string constant identifying the Facebook sign-in method. \n\n #### Declaration\n\n Swift \n\n let FacebookAuthSignInMethod: String\n\n- `\n ``\n ``\n `\n\n ### [GameCenterAuthProviderID](#/c:@FIRGameCenterAuthProviderID)\n\n `\n ` \n @brief A string constant identifying the Game Center identity provider. \n\n #### Declaration\n\n Swift \n\n let GameCenterAuthProviderID: String\n\n- `\n ``\n ``\n `\n\n ### [GameCenterAuthSignInMethod](#/c:@FIRGameCenterAuthSignInMethod)\n\n `\n ` \n @brief A string constant identifying the Game Center sign-in method. \n\n #### Declaration\n\n Swift \n\n let GameCenterAuthSignInMethod: String\n\n- `\n ``\n ``\n `\n\n ### [GitHubAuthProviderID](#/c:@FIRGitHubAuthProviderID)\n\n `\n ` \n @brief A string constant identifying the GitHub identity provider. \n\n #### Declaration\n\n Swift \n\n let GitHubAuthProviderID: String\n\n- `\n ``\n ``\n `\n\n ### [GitHubAuthSignInMethod](#/c:@FIRGitHubAuthSignInMethod)\n\n `\n ` \n @brief A string constant identifying the GitHub sign-in method. \n\n #### Declaration\n\n Swift \n\n let GitHubAuthSignInMethod: String\n\n- `\n ``\n ``\n `\n\n ### [GoogleAuthProviderID](#/c:@FIRGoogleAuthProviderID)\n\n `\n ` \n @brief A string constant identifying the Google identity provider. \n\n #### Declaration\n\n Swift \n\n let GoogleAuthProviderID: String\n\n- `\n ``\n ``\n `\n\n ### [GoogleAuthSignInMethod](#/c:@FIRGoogleAuthSignInMethod)\n\n `\n ` \n @brief A string constant identifying the Google sign-in method. \n\n #### Declaration\n\n Swift \n\n let GoogleAuthSignInMethod: String\n\n- `\n ``\n ``\n `\n\n ### [PhoneMultiFactorID](#/c:@FIRPhoneMultiFactorID)\n\n `\n ` \n @brief The string identifier for using phone as a second factor.\n This constant is available on iOS only. \n\n #### Declaration\n\n Swift \n\n let PhoneMultiFactorID: String\n\n- `\n ``\n ``\n `\n\n ### [TOTPMultiFactorID](#/c:@FIRTOTPMultiFactorID)\n\n `\n ` \n @brief The string identifier for using TOTP as a second factor.\n This constant is available on iOS only. \n\n #### Declaration\n\n Swift \n\n let TOTPMultiFactorID: String\n\n- `\n ``\n ``\n `\n\n ### [PhoneAuthProviderID](#/c:@FIRPhoneAuthProviderID)\n\n `\n ` \n @var FIRPhoneAuthProviderID\n @brief A string constant identifying the phone identity provider.\n This constant is available on iOS only. \n\n #### Declaration\n\n Swift \n\n let PhoneAuthProviderID: String\n\n- `\n ``\n ``\n `\n\n ### [PhoneAuthSignInMethod](#/c:@FIRPhoneAuthSignInMethod)\n\n `\n ` \n @var FIRPhoneAuthProviderID\n @brief A string constant identifying the phone sign-in method.\n This constant is available on iOS only. \n\n #### Declaration\n\n Swift \n\n let PhoneAuthSignInMethod: String\n\n- `\n ``\n ``\n `\n\n ### [TwitterAuthProviderID](#/c:@FIRTwitterAuthProviderID)\n\n `\n ` \n @brief A string constant identifying the Twitter identity provider. \n\n #### Declaration\n\n Swift \n\n let TwitterAuthProviderID: String\n\n- `\n ``\n ``\n `\n\n ### [TwitterAuthSignInMethod](#/c:@FIRTwitterAuthSignInMethod)\n\n `\n ` \n @brief A string constant identifying the Twitter sign-in method. \n\n #### Declaration\n\n Swift \n\n let TwitterAuthSignInMethod: String"]]