Authenticate Using Twitter on Apple Platforms (original) (raw)

You can let your users authenticate with Firebase using OAuth providers like Twitter by integrating generic OAuth Login into your app using the Firebase SDK to carry out the end to end sign-in flow.

Before you begin

Use Swift Package Manager to install and manage Firebase dependencies.

1. In Xcode, with your app project open, navigate to File > Add Packages.
2. When prompted, add the Firebase Apple platforms SDK repository:

https://github.com/firebase/firebase-ios-sdk.git

1. Choose the Firebase Authentication library.
2. Add the -ObjC flag to the Other Linker Flags section of your target's build settings.
3. When finished, Xcode will automatically begin resolving and downloading your dependencies in the background.

To sign in users using Twitter accounts, you must first enable Twitter as a sign-in provider for your Firebase project:

1. Add Firebase to your Apple project.
2. Include the following pods in your Podfile:
   pod 'FirebaseAuth'
3. In the Firebase console, open the Auth section.
4. On the Sign in method tab, enable the Twitter provider.
5. Add the API key and API secret from that provider's developer console to the provider configuration:
   1. Register your app as a developer application on Twitter and get your app's OAuth API key and API secret.
   2. Make sure your Firebase OAuth redirect URI (e.g. my-app-12345.firebaseapp.com/__/auth/handler) is set as your Authorization callback URL in your app's settings page on yourTwitter app's config.
6. Click Save.

Handle the sign-in flow with the Firebase SDK

To handle the sign-in flow with the Firebase Apple platforms SDK, follow these steps:

1. Add custom URL schemes to your Xcode project:
   1. Open your project configuration: double-click the project name in the left tree view. Select your app from the TARGETS section, then select the Info tab, and expand the URL Types section.
   2. Click the + button, and add your Encoded App ID as a URL scheme. You can find your Encoded App ID on theGeneral Settings page of the Firebase console, in the section for your iOS app. Leave the other fields blank.
      When completed, your config should look something similar to the following (but with your application-specific values):
      
2. Create an instance of an OAuthProvider using the provider IDtwitter.com.

Swift

var provider = OAuthProvider(providerID: "twitter.com")  
  

Objective-C

FIROAuthProvider *provider = [FIROAuthProvider providerWithProviderID:@"twitter.com"];

1. Optional: Specify additional custom OAuth parameters that you want to send with the OAuth request.

Swift

provider.customParameters = [  
  "lang": "fr"  
  ]  
  

Objective-C

[provider setCustomParameters:@{@"lang": @"fr"}];  
  

For the parameters Twitter supports, see theTwitter OAuth documentation. Note that you can't pass Firebase-required parameters withsetCustomParameters. These parameters are client_id,redirect_uri, response_type, scope and state. 4. Optional: If you want to customize the way your app presents theSFSafariViewController or UIWebView when displaying the reCAPTCHA to the user, create a custom class that conforms to the AuthUIDelegate protocol, and pass it tocredentialWithUIDelegate. 5. Authenticate with Firebase using the OAuth provider object.

Swift

provider.getCredentialWith(nil) { credential, error in  
  if error != nil {  
    // Handle error.  
  }  
  if credential != nil {  
    Auth.auth().signIn(with: credential) { authResult, error in  
      if error != nil {  
        // Handle error.  
      }  
      // User is signed in.  
      // IdP data available in authResult.additionalUserInfo.profile.  
      // Twitter OAuth access token can also be retrieved by:  
      // (authResult.credential as? OAuthCredential)?.accessToken  
      // Twitter OAuth ID token can be retrieved by calling:  
      // (authResult.credential as? OAuthCredential)?.idToken  
      // Twitter OAuth secret can be retrieved by calling:  
      // (authResult.credential as? OAuthCredential)?.secret  
    }  
  }  
}  
  

Objective-C

[provider getCredentialWithUIDelegate:nil  
                           completion:^(FIRAuthCredential *_Nullable credential, NSError *_Nullable error) {  
  if (error) {  
   // Handle error.  
  }  
  if (credential) {  
    [[FIRAuth auth] signInWithCredential:credential  
                              completion:^(FIRAuthDataResult *_Nullable authResult, NSError *_Nullable error) {  
      if (error) {  
        // Handle error.  
      }  
      // User is signed in.  
      // IdP data available in authResult.additionalUserInfo.profile.  
      // Twitter OAuth access token can also be retrieved by:  
      // authResult.credential.accessToken  
      // Twitter OAuth ID token can be retrieved by calling:  
      // authResult.credential.idToken  
      // Twitter OAuth secret can be retrieved by calling:  
      // authResult.credential.secret  
    }];  
  }  
}];  
  

Using the OAuth access token, you can call theTwitter API.
For example, to get basic profile information, you can call the REST API, passing the access token in the Authorization header:
https://api.twitter.com/labs/1/users?usernames=TwitterDev 6. While the above examples focus on sign-in flows, you also have the ability to link a Twitter provider to an existing user. For example, you can link multiple providers to the same user allowing them to sign in with either.

Swift

Auth().currentUser.link(withCredential: credential) { authResult, error in  
  if error != nil {  
    // Handle error.  
  }  
  // Twitter credential is linked to the current user.  
  // IdP data available in authResult.additionalUserInfo.profile.  
  // Twitter OAuth access token can also be retrieved by:  
  // (authResult.credential as? OAuthCredential)?.accessToken  
  // Twitter OAuth ID token can be retrieved by calling:  
  // (authResult.credential as? OAuthCredential)?.idToken  
  // Twitter OAuth secret can be retrieved by calling:  
  // (authResult.credential as? OAuthCredential)?.secret  
}  
  

Objective-C

[[FIRAuth auth].currentUser  
    linkWithCredential:credential  
            completion:^(FIRAuthDataResult * _Nullable authResult, NSError * _Nullable error) {  
  if (error) {  
    // Handle error.  
  }  
  // Twitter credential is linked to the current user.  
  // IdP data available in authResult.additionalUserInfo.profile.  
  // Twitter OAuth access token is can also be retrieved by:  
  // ((FIROAuthCredential *)authResult.credential).accessToken  
  // Twitter OAuth ID token can be retrieved by calling:  
  // ((FIROAuthCredential *)authResult.credential).idToken  
  // Twitter OAuth secret can be retrieved by calling:  
  // ((FIROAuthCredential *)authResult.credential).secret  
}];

1. The same pattern can be used with reauthenticateWithCredential which can be used to retrieve fresh credentials for sensitive operations that require recent login.

Swift

Auth().currentUser.reauthenticateWithCredential(withCredential: credential) { authResult, error in  
  if error != nil {  
    // Handle error.  
  }  
  // User is re-authenticated with fresh tokens minted and  
  // should be able to perform sensitive operations like account  
  // deletion and email or password update.  
  // IdP data available in result.additionalUserInfo.profile.  
  // Additional OAuth access token is can also be retrieved by:  
  // (authResult.credential as? OAuthCredential)?.accessToken  
  // Twitter OAuth ID token can be retrieved by calling:  
  // (authResult.credential as? OAuthCredential)?.idToken  
  // Twitter OAuth secret can be retrieved by calling:  
  // (authResult.credential as? OAuthCredential)?.secret  
}  
  

Objective-C

[[FIRAuth auth].currentUser  
    reauthenticateWithCredential:credential  
                      completion:^(FIRAuthDataResult * _Nullable authResult, NSError * _Nullable error) {  
  if (error) {  
    // Handle error.  
  }  
  // User is re-authenticated with fresh tokens minted and  
  // should be able to perform sensitive operations like account  
  // deletion and email or password update.  
  // IdP data available in result.additionalUserInfo.profile.  
  // Additional OAuth access token is can also be retrieved by:  
  // ((FIROAuthCredential *)authResult.credential).accessToken  
  // Twitter OAuth ID token can be retrieved by calling:  
  // ((FIROAuthCredential *)authResult.credential).idToken  
  // Twitter OAuth secret can be retrieved by calling:  
  // ((FIROAuthCredential *)authResult.credential).secret  
}];

Handling account-exists-with-different-credential Errors

If you enabled the One account per email address setting in the Firebase console, when a user tries to sign in a to a provider (such as Twitter) with an email that already exists for another Firebase user's provider (such as Google), the errorFIRAuthErrorCodeAccountExistsWithDifferentCredential is thrown along with a temporaryFIRAuthCredential object (Twitter credential). To complete the sign in to the intended provider, the user has to sign first to the existing provider (Google) and then link to the former FIRAuthCredential (Twitter credential). This would look as illustrated below:

Swift

// Sign-in with an OAuth credential. provider.getCredentialWith(nil) { credential, error in // An account with the same email already exists. if (error as NSError?)?.code == AuthErrorCode.accountExistsWithDifferentCredential.rawValue { // Get pending credential and email of existing account. let existingAcctEmail = (error! as NSError).userInfo[AuthErrorUserInfoEmailKey] as! String let pendingCred = (error! as NSError).userInfo[AuthErrorUserInfoUpdatedCredentialKey] as! AuthCredential // Lookup existing account identifier by the email. Auth.auth().fetchProviders(forEmail:existingAcctEmail) { providers, error in // Existing email/password account. if (providers?.contains(EmailAuthProviderID))! { // Existing password account for email. Ask user to provide the password of the // existing account. // Sign in with existing account. Auth.auth().signIn(withEmail:existingAcctEmail, password:password) { user, error in // Successfully signed in. if user != nil { // Link pending credential to account. Auth.auth().currentUser?.linkAndRetrieveData(with: pendingCred) { result, error in // ... } } } } } return }

// Other errors.
if error != nil {
  // handle the error.
  return
}

// Sign in with the credential.
if credential != nil {
  Auth.auth().signInAndRetrieveData(with: credential!) { result, error in
    if error != nil {
      // handle the error.
      return
    }
  }
}

}

Objective-C

// Sign-in with an OAuth credential. [provider getCredentialWithUIDelegate:nil completion:^(FIRAuthCredential *_Nullable credential, NSError *_Nullable error) { // An account with the same email already exists. if (error.code == FIRAuthErrorCodeAccountExistsWithDifferentCredential) { // Get pending credential and email of existing account. NSString *existingAcctEmail = error.userInfo[FIRAuthErrorUserInfoEmailKey]; FIRAuthCredential *pendingCred = error.userInfo[FIRAuthErrorUserInfoUpdatedCredentialKey]; // Lookup existing account identifier by the email. [[FIRAuth auth] fetchProvidersForEmail:existingAcctEmail completion:^(NSArray<NSString *> *_Nullable providers, NSError *_Nullable error) { // Existing email/password account. if ( [providers containsObject:FIREmailAuthProviderID] ) { // Existing password account for email. Ask user to provide the password of the // existing account.

      // Sign in with existing account.
      [[FIRAuth auth] signInWithEmail:existingAcctEmail
                             password:password
                           completion:^(FIRUser *user, NSError *error) {
        // Successfully signed in.
        if (user) {
          // Link pending credential to account.
          [[FIRAuth auth].currentUser linkWithCredential:pendingCred
                                              completion:^(FIRUser *_Nullable user,
                                                           NSError *_Nullable error) {
            // ...
          }];
        }
      }];
    }
  }];
  return;
}

// Other errors.
if (error) {
  // handle the error.
  return;
}

// Sign in with the credential.
if (credential) {
  [[FIRAuth auth] signInAndRetrieveDataWithCredential:credential
      completion:^(FIRAuthDataResult *_Nullable authResult,
                   NSError *_Nullable error) {
    if (error) {
      // handle the error.
      return;
    }
  }];
}

}];

Next steps

After a user signs in for the first time, a new user account is created and linked to the credentials—that is, the user name and password, phone number, or auth provider information—the user signed in with. This new account is stored as part of your Firebase project, and can be used to identify a user across every app in your project, regardless of how the user signs in.

• In your apps, you can get the user's basic profile information from theUser object. See Manage Users.
• In your Firebase Realtime Database and Cloud Storage Security Rules, you can get the signed-in user's unique user ID from the auth variable, and use it to control what data a user can access.

You can allow users to sign in to your app using multiple authentication providers by linking auth provider credentials to an existing user account.

To sign out a user, call signOut:.

Swift

let firebaseAuth = Auth.auth() do { try firebaseAuth.signOut() } catch let signOutError as NSError { print("Error signing out: %@", signOutError) }

Objective-C

NSError *signOutError; BOOL status = [[FIRAuth auth] signOut:&signOutError]; if (!status) { NSLog(@"Error signing out: %@", signOutError); return; }

You may also want to add error handling code for the full range of authentication errors. See Handle Errors.