Question

I have a small app that attempts to do basic login with FB using the exact methodology used in the Facebook tutorial for logging in here: https://developers.facebook.com/docs/howtos/login-with-facebook-using-ios-sdk/

The desired behavior is that the user be able to login to FB and stay logged in until they have explicitly chosen to log out by clicking on the logout button. They should stay logged in across launches of the app, even if the app is forcibly killed (but not deleted).

What is happening is that after clicking on the Login button, the app correctly logs the user in, but once I navigate back to the root view controller, and then back to the FacebookViewController, the button shows Login again, instead of log out. Something somewhere is killing the session.

I am not sure what code will be asked for, but here is a bunch:

#import "FacebookViewController.h"

@interface FacebookViewController ()

@end

@implementation FacebookViewController
@synthesize authButton;
@synthesize postSwitch;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.

    [[NSNotificationCenter defaultCenter]
     addObserver:self
     selector:@selector(sessionStateChanged:)
     name:FBSessionStateChangedNotification
     object:nil];

    // Check the session for a cached token to show the proper authenticated
    // UI. However, since this is not user intitiated, do not show the login UX.
    AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
    [appDelegate openSessionWithAllowLoginUI:NO];

    // Set toggle
    if ([[[NSUserDefaults standardUserDefaults] objectForKey:@"postToFB"] isEqualToString:@"Yes"]) {
        //set to yes
        [postSwitch setOn:YES animated:YES];
    } else {
        // set to no
        [postSwitch setOn:NO animated:YES];
    }

    NSLog(@"postToFB is now %@",[[NSUserDefaults standardUserDefaults] objectForKey:@"postToFB"]);
}

- (IBAction)authButtonAction:(id)sender
{
    AppDelegate *appDelegate =
    [[UIApplication sharedApplication] delegate];

    // If the user is authenticated, log out when the button is clicked.
    // If the user is not authenticated, log in when the button is clicked.
    if (FBSession.activeSession.isOpen) {
        [appDelegate closeSession];
    } else {
        // The user has initiated a login, so call the openSession method
        // and show the login UX if necessary.
        [appDelegate openSessionWithAllowLoginUI:YES];
    }
}

- (IBAction)togglePostSwitch:(id)sender
{
    if ([[[NSUserDefaults standardUserDefaults] objectForKey:@"postToFB"] isEqualToString:@"Yes"]) {
        //set to No
        [[NSUserDefaults standardUserDefaults] setObject:@"No" forKey:@"postToFB"];
    } else {
        // set to yes
        [[NSUserDefaults standardUserDefaults] setObject:@"Yes" forKey:@"postToFB"];
    }

    NSLog(@"postToFB is now %@",[[NSUserDefaults standardUserDefaults] objectForKey:@"postToFB"]);
}

- (void)sessionStateChanged:(NSNotification*)notification
{
    if (FBSession.activeSession.isOpen) {
        [self.authButton setTitle:@"Logout of Facebook" forState:UIControlStateNormal];

    } else {
        [self.authButton setTitle:@"Login to Facebook" forState:UIControlStateNormal];

    }
}

@end

The MainViewController (the root VC) has the following in the ViewDidLoad, and the ViewWillAppear:

- (void)viewDidLoad
{
    [[self navigationController] setNavigationBarHidden:YES animated:NO];
    AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
    BOOL open = [appDelegate openSessionWithAllowLoginUI:NO];
    if (open) {
        NSLog(@"User session found (MainVC viewDidLoad)");
    } else {
        NSLog(@"no session detected");
    }


}


- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:NO];
    [[self navigationController] setNavigationBarHidden:YES animated:NO];
}

I am not real clear on why this behavior is occurring. Any help would be greatly accepted 🙂

Answer 1

I actually traced this back to an error in labeling the login button. The session was always open even when the button said ‘log in’. I managed to correct this issue, but now I am discovering that indeed the app will not stay logged in across launches, but at least the login/logout button is always correct!