Passing a ManagedObjectContext to a second view
- by amo
I'm writing my first iPhone/Cocoa app. It has two table views inside a navigation view. When you touch a row in the first table view, you are taken to the second table view. I would like the second view to display records from the CoreData entities related to the row you touched in the first view.
I have the CoreData data showing up fine in the first table view. You can touch a row and go to the second table view. I'm able to pass info from the selected object from the first to the second view. But I cannot get the second view to do its own CoreData fetching. For the life of me I cannot get the managedObjectContext object to pass to the second view controller. I don't want to do the lookups in the first view and pass a dictionary because I want to be able to use a search field to refine results in the second view, as well as insert new entries to the CoreData data from there.
Here's the function that transitions from the first to the second view.
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
// Navigation logic may go here -- for example, create and push another view controller.
NSManagedObject *selectedObject = [[self fetchedResultsController] objectAtIndexPath:indexPath];
SecondViewController *secondViewController = [[SecondViewController alloc] initWithNibName:@"SecondView" bundle:nil];
secondViewController.tName = [[selectedObject valueForKey:@"name"] description];
secondViewController.managedObjectContext = [self managedObjectContext];
[self.navigationController pushViewController:secondViewController animated:YES];
[secondViewController release];
}
And this is the function inside SecondViewController that crashes:
- (void)viewDidLoad {
[super viewDidLoad];
self.title = tName;
NSError *error;
if (![[self fetchedResultsController] performFetch:&error]) { // <-- crashes here
// Handle the error...
}
}
- (NSFetchedResultsController *)fetchedResultsController {
if (fetchedResultsController != nil) {
return fetchedResultsController;
}
/*
Set up the fetched results controller.
*/
// Create the fetch request for the entity.
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
// Edit the entity name as appropriate.
// **** crashes on the next line because managedObjectContext == 0x0
NSEntityDescription *entity = [NSEntityDescription entityForName:@"SecondEntity" inManagedObjectContext:managedObjectContext];
[fetchRequest setEntity:entity];
// <snip> ... more code here from Apple template, never gets executed because of the crashing
return fetchedResultsController;
}
Any ideas on what I am doing wrong here?
managedObjectContext is a retained property.
UPDATE: I inserted a NSLog([[managedObjectContext registeredObjects] description]); in viewDidLoad and it appears managedObjectContext is being passed just fine. Still crashing, though.
Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '+entityForName: could not locate an NSManagedObjectModel for entity name 'SecondEntity''
