Passing a managed object context with a tab controller

Question

Okay, I've tried to figure this out over and over again.

I know the best practice is to have the App Delegate pass the managed object context to the first view controller in an application, and then have each subsequent view controller pass the managed object context down. However, when I'm using a Tab Bar Controller in my application, I can seem to wrap my head around that extra layer.

The only way I've been able to figure out how to do it is have the root view controller of each tab "Reach Back" into the app delegate to grab the context, but as I understand it this is poor form.

Answer 1

You can use interface builder to achieve the same thing.

Here is a slightly modified (for some additional clarity) version of Rog's original suggestion - notice the IBOutlet's

@interface AppDelegate : NSObject <UIApplicationDelegate> {
    ViewController1 *vc1;
    ViewController2 *vc2;
    ViewController3 *vc3;
}

@property (nonatomic, retain) IBOutlet ViewController1 *vc1;
@property (nonatomic, retain) IBOutlet ViewController2 *vc2;
@property (nonatomic, retain) IBOutlet ViewController3 *vc2;

Then on the implementation file:

- (void)applicationDidFinishLaunching:(UIApplication *)application {
       vc1.managedObjectContext = self.managedObjectContext;
       vc2.managedObjectContext = self.managedObjectContext;
       vc3.managedObjectContext = self.managedObjectContext;
       // Continue with your implementation logic
}

Then from within Interface Builder ctrl drag from your App Delegate to the View Controller nested within the Tab Bar Controller and hook up the relevant View controller from the contextual menu that appears.