Objective C communication between classes

Question

Hi All.

I have an AppController class that looks after view/control in my app in the usual way.

There's a button on my app's main window in IB that causes AppController to instantiate a new window controller (accountPanelController) and show that secondary window:

- (IBAction) showAccountPanel:(id) sender
{
    //Is accountController nil?
    if (!accountPanelController) {
     accountPanelController = [[AccountPanelController alloc] init];
    }

    [accountPanelController showWindow:self];
}

When that new window is done with, I want to send the data collected from my secondary window controller to a method in AppController:

- (IBAction) close: (id) sender
{
    NSLog(@"Close detected");
    [AppController addAccount:0];
    [self close];
}

However, when I try and call the addAccount method in AppController from the new window controller, I get an "'AppController' may not respond to '+addAccount'" warning.

This seems to be related to AppController being a class rather than an object instantiation, since the method in AppController is called -addAccount (rather than the +addAccount reported in the warning). Indeed, if I change the name of the target method to +addAccount instead of -addAccount, the warning does not appear (but the program crashes on execution).

Given that I don't actually instantiate AppController myself (I guess that happens somehow during NIB initiation), does anyone have any ideas how I can send the data to the AppController method? Notifications seem like overkill...

Many thanks.

Answer 1

I recommend the following introduction article on Apple's Mac Dev Center: Communicate with Objects - #Notifications
Update:
I pointed the link to to relevant anchor (Notifications).

The problem in your code sample is, that you call a class method (those with a +), but you implement an instance method (-).
So a simple fix would be, to get the (shared)instance of your AppController (probably self in your code) and send it the addAccount: message.
But I encourage you to read the article first.

Maybe you can solve your problem by sending a notification (NSNotification) from your view to your controller.

Update:
Another interesting read for you might be this SO question regarding the difference between class methods and instance methods.

Answer 2

Just supply an intiWithOtherController method and add it herre:

accountPanelController = [[AccountPanelController alloc] initWithOtherController:self];

just pass self, so you need something like this:

(AccountPanelController *) initWithOtherController:(OtherController *)

now you have a pointer to otherController and you can do:

[otherController addAccount:0]