Help with "Cannot perform operation without a managed object context"

Question

I have an NSViewController with its own nib that requires access to the managedObjectContext to display objects in a tableview. This is how I have the managed object context set up in my view controller:

@interface {
    ...
    NSManagedObjectContext* managedObjectContext;
    ...
}

@property (nonatomic, retain) NSManagedObjectContext* managedObjectContext;

@implementation {
    ...
    @synthesize managedObjectContext;
    ...
}

in awakeFromNib I initialize it as follows:

managedObjectContext = [[NSApp delegate] managedObjectContext];

I have the tableview hooked up to an NSArrayController in interface builder (exactly as in this tutorial) and I have its managedObjectContext set to my view controller's managedObjectContext.

What could be the source of this error?

Answer 1

Set a breakpoint in your -awakeFromNib method and verify your app delegate returns a valid object or is a valid object itself at this point. I'll bet it's nil. The context may not be created yet because your view controller may have been awoken before the app delegate.