Use the Login with Amazon SDK for iOS APIs

LWA for iOS

STEP 1:
Install the LWA SDK for iOS

→

STEP 2:
Run the Sample App

→

STEP 3:
Register with LWA

→

STEP 4:
Create a LWA Project

→

STEP 5:
Add a LWA Button to Your App

→

STEP 6:
Use the LWA SDK for iOS APIs

→

STEP 7:
Integrate with Your Account System

Connect the AppDelegate
Handle the Login Button and Get Profile Data
Fetch User Profile Data
Check for User Login at Startup
Clear Authorization Data and Log Out Users
Test your Integration

Connect the AppDelegate

Implement application:openURL:options: in the class in your project that handles the UIApplicationDelegate protocol. By default, this will be the AppDelegate class. When a user successfully logs into your app using Login with Amazon, they will be redirected from the Amazon login screen back to your app based on the URL Scheme you added to your App Property List earlier. In order to handle this redirect, you must implement the application:openURL:options: method, which returns YES if the URL is successfully handled.

The Login with Amazon SDK for iOS provides a library function, handleOpenURL:sourceApplication: which handles any redirect URL sent from Amazon pages. It returns YES if the URL is successfully handled by the SDK. Call this method within the application:openURL:options: method.

To invoke this method, you will need to import <LoginWithAmazon/LoginWithAmazon.h>.

import <LoginWithAmazon/LoginWithAmazon.h>

    @implementation AppDelegate
    - (BOOL)application:(UIApplication *)application openURL:(NSURL *)
        url options:(NSDictionary<uiapplicationopenurloptionskey,id> *)options {

        	return [AMZNAuthorizationManager handleOpenURL:url 	
            sourceApplication:options[UIApplicationOpenURLOptionsSourceApplicationKey]];
      }
    @end

This section explains how to call the authorize:withHandler: API to login a user. This includes creating an onLoginButtonClicked: listener for your Login with Amazon button.

Add Login with Amazon to your iOS project. For instructions, see Create a Login with Amazon Project.
Import the Login with Amazon API to your source file.

To import the Login with Amazon API, add the following #import statements to your source file:
```
#import <LoginWithAmazon/LoginWithAmazon.h>
```
Call authorize:withHandler: in onLoginButtonClicked.

If you followed the steps in Add a Login with Amazon Button to Your App, you should have an onLoginButtonClicked: method linked to a Login with Amazon button. In that method, call authorize:withHandler: to prompt the user to login and authorize your application.

This method will enable the user to sign in and consent to the requested information in one of the following ways:
1. Switches to web view in a secure context (if the Amazon Shopping app is installed to the device)
2. Switches to Safari View Controller (on iOS 9 and later)
3. Switches to the system browser (on iOS 8 and earlier)
The secure context for the first option is available when the Amazon Shopping app is installed to the device. If the user is already signed in to the Amazon Shopping app, this API will skip the sign in page, leading to a Single Sign-On (SSO) experience. See Customer Experience for iOS apps to learn more.

The first parameter to authorize:withHandler: is an AMZNAuthorizeRequest object that indicates what scope your application is requesting authorization for. A scope encompasses the user data you are requesting from Login with Amazon. The first time a user logs in to your app, they will be presented with a list of the data you are requesting and asked for approval.

Login with Amazon currently supports the following scopes: profile (gives access to the user’s name, email address, and Amazon account ID), profile:user_id (gives access to the user’s Amazon account ID only), and postal_code (gives access to the user’s zip/postal code on file for their Amazon account).

Use the methods defined in AMZNProfileScope to get a scope object and add it to your AMZNAuthorizeRequest object. See the sample code below for details.

The second parameter to authorize:withHandler: is AMZNAuthorizationRequestHandler, described in the next step.

Create an AMZNAuthorizationRequestHandler block object.

AMZNAuthorizationRequestHandler processes the result of the authorize:withHandler: call. To learn more about objective-c blocks, see Working with Blocks on developer.apple.com.

The first parameter of AMZNAuthorizationRequestHandler is an AMZNAuthorizeResult object. After a user is authorized successfully, AMZNAuthorizeResult will contain an access token which can be used to access a user’s profile data, and an AMZNUser object, which contains the user’s profile data.

The second parameter of AMZNAuthorizationRequestHandler is a Boolean called userDidcancel. This parameter will be set to true if the user:

Closes the Safari View Controller during login and authorization (on iOS 9 and later)
Closes the sign in or consent screens from the web view in the Amazon Shopping app
Cancels the login or rejects authorization

The third parameter of AMZNAuthorizationRequestHandler is an NSError object which contains error details if the login and authorization fails due to the SDK or authorization server.

    - (IBAction)onLogInButtonClicked:(id)sender {
      // Build an authorize request.
      AMZNAuthorizeRequest *request = [[AMZNAuthorizeRequest alloc] init];
        	request.scopes = [NSArray arrayWithObjects:
        	// [AMZNProfileScope userID],
        	[AMZNProfileScope profile],
        	[AMZNProfileScope postalCode]];

      // Make an Authorize call to the Login with Amazon SDK.
      [[AMZNAuthorizationManager sharedManager] authorize:request
        withHandler:^(AMZNAuthorizeResult *result, BOOL
        userDidCancel, NSError *error) {
        	  if (error) {
          		// Handle errors from the SDK or authorization server.
        	  } else if (userDidCancel) {
          		// Handle errors caused when user cancels login.
        	  } else {
          		// Authentication was successful.
          		// Obtain the access token and user profile data.
          		NSString *accessToken = result.token;
          		AMZNUser *user = result.user;
          		NSString *userID = user.userID;
          }
      }];
    }

Fetch User Profile Data

As long as a user is logged in and authorized to your app, you can fetch their user profile data at any time. This section explains how to use the fetch: method of the AMZNUser class to retrieve the most up-to-date user profile data for users who are currently authorized. The profile data you can retrieve is based on the scope indicated in the authorize call.

Call AMZNUser fetch:.

This method will fetch profile data via an AMZNUserFetchRequestHandler block object. The first parameter to AMZNUserRequestHandler is an AMZNUser object. The AMZNUser object can include a userID, name, email, and postalCode, depending on the requested scope.

[AMZNUser fetch:^(AMZNUser *user, NSError *error) {
      if (error) {
        // Error from the SDK, or no user has authorized to the app.
      } else if (user) {
        NSString *userID = user.userID;
        //NSString *name = user.name;
        //NSString *email = user.email;
        //NSString *postalCode = user.postalCode;
      }
    }];

If a user logs into your app, closes the app, and restarts the app later, the app is still authorized to retrieve data. The user is not logged out automatically. At startup, you can show the user as logged in if your app is still authorized. This section explains how to use authorize:withHandler: to see if the app is still authorized.

Create an AMZNAuthorizeRequest object and specify scopes that indicate the user data your application is requesting authorization for. For more information on scopes, see Handle the Login Button and Get Profile Data above.

Set AMZNAuthorizeRequest.interactiveStrategy to AMZNInteractiveStrategyNever. AMZNAuthorizeRequest supports multiple strategies for prompting user login:

AMZNInteractiveStrategyAuto (default): The SDK looks for a locally stored authorization grant from previous authorize:withHandler: responses. If one is available, valid, and contains all requested scopes, the SDK will return a successful response via AMZNAuthorizationRequestHandler, and will not prompt the user to login. Otherwise, the user will be prompted to login.
AMZNInteractiveStrategyAlways: The SDK will always prompt the user to login regardless of whether they have previously been authorized to use the app. When the user is prompted, the SDK will remove all locally cached authorization grants for the app.
AMZNInteractiveStrategyNever: The SDK looks for a locally stored authorization grant from previous authorize:withHandler responses. If one is available, valid, and contains all requested scopes, the SDK will return an AMZNAuthorizeResult object that contains an access token and user profile data. Otherwise, it will return an NSError object via AMZNAuthorizationRequestHandler.

    // Build an authorize request.
       AMZNAuthorizeRequest *request = [[AMZNAuthorizeRequest alloc] init];
        request.scopes = [NSArray arrayWithObjects:
      // [AMZNProfileScope userID],
         [AMZNProfileScope profile],
        [AMZNProfileScope postalCode]];

       request.interactiveStrategy = AMZNInteractiveStrategyNever;

       [[AMZNAuthorizationManager sharedManager] authorize:request
         withHandler:^(AMZNAuthorizeResult *result, BOOL
          userDidCancel, NSError *error) {
            if (error) {
                 // Error from the SDK, indicating the user was not previously authorized to your app for the requested scopes.
             } else {
                 // The user was previously authorized to your app.
                 // Obtain the access token and user profile data.
            	     NSString *accessToken = result.token;
                 AMZNUser *user = result.user;
                 NSString *userID = user.userID;
          	   }
           }];

Clear Authorization Data and Log Out Users

This section explains how to use the signOut method to clear the user's authorization data from both the AMZNMobileLib (AMZNMobileLib was renamed from AIMobileLib in Login with Amazon for iOS version 3.1.0) local data store, and the authorization server. The user will have to login again in order for the app to retrieve profile data. Use this method to log out a user, or to troubleshoot login problems in the app.

Implement a logout mechanism.

When a user has successfully logged in, you should provide a logout mechanism so they can clear their profile data and previously authorized scopes. Your mechanism might be a hyperlink, button, or a menu item.
Call signOut:.

Call signOut: in your logout handler to remove a user's authorization data (access tokens, profile) from the local store, and their authentication state from the server. The input parameter to signOut is an AMZNAuthorizationRequestHandler block object. The block should detect and handle NSError objects, which are returned when signOut: fails.
```
    [[AMZNAuthorizationManager sharedManager] signOut:^(NSError * _Nullable error) {
      if (!error) {
        // error from the SDK or Login with Amazon authorization server.
      }
    }];
```

Test your Integration

Launch your app in an iOS device or simulator and confirm you can log in with your Amazon.com credentials.

Important: When testing on iOS10 simulators, you may see the error message APIKey for the Application is invalid for an authorizeUserForScopes request, or Unknown Error Code for an clearAuthorizationState request. This is a known bug with Apple which occurs when the SDK tries to access the keychain. Until Apple resolves the bug, you can work around it by enabling Keychain Sharing for your app under the Capabilities tab of your app's target. This bug only impacts simulators. You can test on actual iOS10 devices without using any workaround.