Google + iPhone API sign in and share without leaving app
google-plus, iphone
Solution
So, it depends what you want to do.
Sign-In: this will always call out to another application. If the Google+ application is installed it will call out to that, else it will fall back to Chrome and Safari.
Sharing/Interactive Posts: right now this always uses Chrome or Mobile Safari.
Retrieving friends, writing app activities, retrieving profile information: All this is done with the access token retrieved after sign in, so does not require leaving the application.
It is possible, though rather unsupported, to skip the SDK and pop up a UIWebView, construct the OAuth link dynamically and send the user to that (take a look at GTMOAuth2ViewControllerTouch in the open source libraries that ship with the SDK). Below is the a very rough example of the kind of thing you could do to plumb it back into the GPPSignIn instance.
However, you would be guaranteeing that the user has to enter their username and password (and maybe 2nd factor). With the Google+ app you're pretty much guaranteed to be already signed in, and with the Chrome/Safari route, there is a chance the user is already signed in (particularly if they're using other apps with Google+ Sign-In).
This also doesn't address sharing, so I would strongly recommend using the existing SDK as far as possible. Filing a feature request for the way you would prefer it to work would be a good thing to do as well: https://code.google.com/p/google-plus-platform/issues/list
@interface ViewController() {
GTMOAuth2ViewControllerTouch *controller;
}
@end;
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
GPPSignIn *signIn = [GPPSignIn sharedInstance];
signIn.clientID = @""; // YOUR CLIENT ID HERE.
signIn.delegate = self;
}
- (IBAction)didTapSignIn:(id)sender {
void (^handler)(id, id, id) =
^(GTMOAuth2ViewControllerTouch *viewController,
GTMOAuth2Authentication *auth,
NSError *error) {
[self dismissViewControllerAnimated:YES completion:^{
[controller release];
}];
if (error) {
NSLog(@"%@", error);
return;
} else {
BOOL signedIn = [[GPPSignIn sharedInstance] trySilentAuthentication];
if(!signedIn) {
NSLog(@"Sign In failed");
}
}
};
controller = [[GTMOAuth2ViewControllerTouch
controllerWithScope:kGTLAuthScopePlusLogin
clientID:[GPPSignIn sharedInstance].clientID
clientSecret:nil
keychainItemName:[GPPSignIn sharedInstance].keychainName
completionHandler:handler] retain];
[self presentViewController:controller animated:YES completion:nil];
}
- (void)finishedWithAuth:(GTMOAuth2Authentication *)auth
error:(NSError *)error {
if (!error) {
UIAlertView * al = [[UIAlertView alloc] initWithTitle:@"Authorised"
message:@"Authorised!"
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil];
[al show];
[al release];
}
}
The only real trick to this code is that it uses the [GPPSignIn sharedInstance].keychainName - this means that the auth tokens get stored in the same keychain entry as the GPPSignIn button would, which in turn means we can use [[GPPSignIn sharedInstance] trySilentAuthentication] once it has been populated, and keep the same callback based flow as the main library.
Problem
I recently integrated the Google + API in my App, it was a breeze, my only problem with it, is that everything requires you to leave the app and then come back (it uses URL schemes for this). This is not the behavior I would like, is there a way to directly call their services and do whatever I want with the responses just like in LinkedIn API?. I really want to avoid going back and forth between safari and my app. Any suggestions/documentation is appreciated. Thank you, Oscar