Trigger a segue from AppDelegate

Question

I'm a noob to iOS dev and I'm trying to implement a simple Facebook Connect, but when the user is logged in I want the app to change view automatically.

In my storyboard I have the FacebookLoginViewController that is embeded inside a NavigationController. Then I've added a segue between FacebookLoginViewController and UploadViewController (where I let the user pick an image and upload it to AWS S3).

I've check the Facebook Sample to inspire me.

The problem I'm facing is with the segue between FacebookLoginViewController and UploadViewController. This Segue has the following identifier: LoginSuccessSegue

In AppDelegate, when a session state change, the following method is called: - (void)sessionStateChanged:(FBSession *)session state:(FBSessionState) state error:(NSError *)error

In this method, when the user is logged in, another method is called: userLoggedIn

Now, what I want to do here is trigger the Segue to perform the push transition between FacebookLoginViewController and UploadViewController. And I have to do it from the AppDelegate because it's here that the session state is checked.

I've tried to instantiate FacebookLoginViewController and call a method I've defined to trigger the segue.

In AppDelegate.m:

// Show the user the logged-in UI
- (void)userLoggedIn
{
    // Switch view to pick image
    FacebookLoginViewController *LoginController = [[FacebookLoginViewController alloc] init];
    [LoginController successLoginTransition];
}

In FacebookLoginViewController.m:

-(void)successLoginTransition
{
    [self performSegueWithIdentifier:@"LoginSuccessSegue" sender:self];
}

But doing so I end up with the following error:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Receiver () has no segue with identifier 'LoginSuccessSegue''

---

To make sure the Segue is working, I've created a button in the FacebookLoginViewController that is calling the following method:

-(IBAction)testSegue:(id)sender
{
    [self performSegueWithIdentifier:@"LoginSuccessSegue" sender:self];
}

And this is working.

---

I've tried to search for this error but I could find anything helpful.

Can you please tell me what am I doing wrong and maybe how I should do to trigger this transition?

Cheers, Maxime

Answer 1

Don't alloc init the UIViewController because you are using storyboards.

Change

- (void)userLoggedIn
{
    // Switch view to pick image
    FacebookLoginViewController *LoginController =
                                          [[FacebookLoginViewController alloc] init];
    [LoginController successLoginTransition];
}

to

- (void)userLoggedIn
{
    // Switch view to pick image
    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main_iPhone" 
                                                         bundle:nil];
    FacebookLoginViewController *LoginController = 
                 [storyboard instantiateViewControllerWithIdentifier:@"FbLoginView"];
    [LoginController successLoginTransition];
}

EDIT:

You want to naviguate to the image Picker, no need to make the LoginController push a segue. you can just do it directly:

- (void)userLoggedIn
{
    // Switch view to pick image
    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main" bundle:nil];
    pickImageViewController *LoginController = [storyboard instantiateViewControllerWithIdentifier:@"pickImageView"];
    [(UINavigationController*)self.window.rootViewController pushViewController:LoginController animated:NO];
}