Passed instance of NSManagedObject turns into fault - RKManagedObjectStore

Question

I have a weird problem related to passing an instance of a NSManagedObject to another viewcontroller.

I pass an instance of NSManagedObject fetched from a NSFetchResultsController like so: to another viewcontroller.

- (void)tableView:(UITableView*)tableView didSelectRowAtIndexPath:(NSIndexPath*)indexPath
{

    Product* product = (Product*)[self.fetchedResultsController objectAtIndexPath:indexPath];

    DetailViewController* pDetailVC = [self.storyboard instantiateViewControllerWithIdentifier:@"DetailViewController"];

    pDetailVC.product = product;
    pDetailVC.managedObjectContext = self.managedObjectContext;

    [self.navigationController pushViewController:pDetailVC
                                         animated:YES];
}

I am using Restkit and my managedObjectContext is the RKManagedObjectStore mainQueueManagedObjectContext.

My application does also consists of an UITabbarController.

I then access the passed objects properties in the cellForAtIndexPath in the viewcontroller which the object is passed to, like so:

cell.descLabel.text = self.product.info;

In my viewDidAppear method of this viewcontroller I reload the tableView, to show the data of the passed instance. This works fine the first time, when the object is passed to the viewcontroller, but if I then switch to another viewcontroller using the tabbar and then return to the viewcontroller, all the data of the passed object is null, it has been turned into a fault.

How can I prevent this for happening, prevent that the data is null/faulted when I come back to the viewcontroller?

Answer 1

The viewDidAppear is called each time you switch to that tabBar, not sure of why is causing a fault on your NSManagedObject, that would depend if your are making other changes on the same context.

If you are using this NSmanagedObject just to display its properties, I recommend you pass your NSmanagedObject info to a custom NSObject subclass and use that object on your table data source