Snippet of code for handling Twitter multiple login using Firebase Simple Login

TwitterTest.m

@interface TwitterTest()
 
@property (strong, nonatomic) NSString *currentTwitterHandle;
 
@end
 
@implementation TwitterTest // Note, must conform to the <UIActionSheetDelegate> protocol
 
- (void)authenticateWithTwitter;
{
    if (self.currentTwitterHandle) {
        // If the user has a currently selected twitter handle, log them in normally
        Firebase *ref = [[Firebase alloc] initWithUrl:@"https://<your-firebase>.firebaseio.com"];
        FirebaseSimpleLogin *authRef = [[FirebaseSimpleLogin alloc] initWithRef:ref];
        [authRef loginToTwitterAppWithId:@"TWITTER_APP_ID" multipleAccountsHandler:^int(NSArray *usernames) {
            return (int)[usernames indexOfObject:self.currentTwitterHandle];
        } withCompletionBlock:^(NSError *error, FAUser *user) {
            if (error != nil) {
                // An error has occurred!
            } else {
                // We have a user
                self.title = self.currentTwitterHandle;
            }
        }];
    } else {
        // Access account store to pull twitter accounts on device
        ACAccountStore *accountStore = [[ACAccountStore alloc] init];
        ACAccountType *accountType = [accountStore accountTypeWithAccountTypeIdentifier:ACAccountTypeIdentifierTwitter];
        [accountStore requestAccessToAccountsWithType:accountType options:nil completion:^(BOOL granted, NSError *error) {
            if (granted) {
                NSArray *accounts = [accountStore accountsWithAccountType:accountType];
                [self handleMultipleTwitterAccounts:accounts];
            }
        }];
    }
}
 
- (void)handleMultipleTwitterAccounts:(NSArray *)accounts;
{
    switch ([accounts count]) {
        case 0:
            // Deal with setting up a twitter account (could also not be set up on the device, deal with this differently)
            [[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"https://twitter.com/signup"]];
            break;
            
        case 1:
            // Single user system, go straight to login
            self.currentTwitterHandle = [[accounts firstObject] username];
            [self authenticateWithTwitter];
            break;
            
        default:
            // Handle multiple users
            [self selectTwitterAccount:accounts];
            break;
    }
}
 
- (void)selectTwitterAccount:(NSArray *)accounts;
{
    // Pop up action sheet which has different user accounts as options
    UIActionSheet *selectUserActionSheet = [[UIActionSheet alloc] initWithTitle:@"Select Twitter Account" delegate:self cancelButtonTitle:nil destructiveButtonTitle:nil otherButtonTitles: nil];
    for (ACAccount *account in accounts) {
        [selectUserActionSheet addButtonWithTitle:[account username]];
    }
    selectUserActionSheet.cancelButtonIndex = [selectUserActionSheet addButtonWithTitle:@"Cancel"];
    [selectUserActionSheet showInView:self.view];
}
 
- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex;
{
    self.currentTwitterHandle = [actionSheet buttonTitleAtIndex:buttonIndex];
    [self authenticateWithTwitter];
}
 
@end