如何使用故事板将对象从AppDelegate传递到WindowController？

Question

In my application delegate I create a NSManagedObjectContext property that I want to pass to the window controller I launch in applicationDidFinishLaunching: .

This is basically my code in AppDelegate.m :

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
    NSStoryboard *storyboard = [NSStoryboard storyboardWithName:@"Main" bundle:nil];

    self.setupWindowController = [storyboard instantiateControllerWithIdentifier:@"setup"];
    self.setupWindowController.managedObjectContext = self.managedObjectContext;

    [self.setupWindowController showWindow:self];
}

In MyWindowController.m I have the following method:

- (void)setManagedObjectContext:(NSManagedObjectContext *)managedObjectContext {
    ((MyViewController *)self.contentViewController).managedObjectContext = managedObjectContext;
}

And this is a method from MyViewController.m :

- (void)prepareForSegue:(NSStoryboardSegue *)segue sender:(id)sender {
    if ([segue.destinationController isKindOfClass:self.class]) {
        ((MyViewController *)segue.destinationController).managedObjectContext = self.managedObjectContext;
    }
}

This approach worked pretty well until I had to programmatically launch different windows from the application delegate. The problem now is that prepareForSegue:sender: for the initial view is called before I'm able to set the MyWindowController.managedObjectContext , so it'll only pass nil with the following segues.

How on earth should I pass objects from my app delegate to the initial window controller before it sets up the view hierarchy?

Am I approaching all this the wrong way?

Answer 1

I suggest reducing the dependencies among controllers by making a data model layer in your application.

The data model would manage the information that the controllers use and provide an application-specific facade in front of CoreData. The data model object(s) can be shared instances or can be requested from a known object, such as the app delegate.

That way, the model is only referenced where needed and doesn't clutter interfaces just as a pass-through object.