问题

I am trying to create a share extension for my application which requires to login to Google from the extension. I've setup the sharing group keychain and am able to write from the main application and read the extension target. But I can't login to Google from the extension because GIDSignIn.sharedInstance().hasAuthInKeychain() always returns false.

Is there any way to login to Google from an extension and how do I do that? Any help would be appreciated.

回答1:

1. In Bridging-Header.h

import <GoogleSignIn/GoogleSignIn.h>
import <Google/Core.h>

2. In AppDelegate.swift

import Google

In application:didFinishLaunchingWithOptionslaunchOptions: configure the GGLContext object:

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
var configureError: NSError?
        GGLContext.sharedInstance().configureWithError(&configureError)
        assert(configureError == nil, "Error configuring Google services: \(configureError)")
        GIDSignIn.sharedInstance().clientID = "client id"
        GIDSignIn.sharedInstance.shouldFetchBasicProfile = true
        GIDSignIn.sharedInstance().delegate = self
}

Then, add a GIDSignInButton view to your app.

Lastly, in the view controller, implement the signIn:didSignInForUser: delegate method that will be called when the sign-in button is tapped: when authorizing the app.

- (void)signIn:(GIDSignIn *)signIn
    didSignInForUser:(GIDGoogleUser *)user
           withError:(NSError *)error {
  // Perform any operations on signed in user here.
  // ...
}

3. Sharing Credentials between apps/extensions

When you sign-in the Google framework will have to use native iOS methods to add the new credentials to the iOS Keychain. Thus they will be using the SecItemAdd(_:_:) method that will add one or more items to a keychain.

To access the same keychain item in both the app and the extension, you need to enable the "Keychain Sharing" for both the app and the extension from the Xcode's Capabilities section in your project settings. When you do this, Xcode will probably want to update your app ID and provisioning profiles, because they need to reflect this new capability. You'll probably have to reauthorize the app (Step 2) to get the credentials into the right group.

Apple Documentation clearly states:

If you want the new keychain item to be shared among multiple applications, include the kSecAttrAccessGroup key in the attributes dictionary. The value of this key must be the name of a keychain access group to which all of the programs that will share this item belong.

When you use Xcode to create an application, Xcode adds an application-identifier entitlement to the application bundle. Keychain Services uses this entitlement to grant the application access to its own keychain items. You can also add a keychain-access-groups entitlement to the application and, in the entitlement property list file, specify an array of keychain access groups to which the application belongs.

4. Extra Hints from Google that I haven't mentioned above.

Please see "Google Sign-In for iOS". Here is sample code to use GIDSignIn:

Get a reference to the GIDSignIn shared instance: GIDSignIn *signIn = [GIDSignIn sharedInstance];
Set the OAuth 2.0 scopes you want to request: [signIn setScopes:[NSArray arrayWithObject:@"https://www.googleapis.com/auth/plus.login"]];
Call [signIn setDelegate:self];
Set up delegate method signIn:didSignInForUser:withError:.
Call handleURL on the shared instance from application:openUrl:... in your app delegate.
Call signIn on the shared instance;

回答2:

To do this you need to enable Keychain Sharing in your project's "Capabilities" pane. This will allow both the extension and the main app to share the password.

Apple's documentation on Keychain Sharing is here.

回答3:

No answer until now. I finally rewrite the Google login by using Aerogear framework. Now I can able to login from both main target and extension target. This also fix this google logout issue.

来源：https://stackoverflow.com/questions/39139160/retrieve-google-user-from-ios-extension

Retrieve google user from ios extension

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