Why I do not need to free managedObjectContext in the second TableViewController

Question

I have two table controllers showing CoreData objects. One is a detailed view (with sentences), one of them is a review (with stories). Select a story → See Suggestions.

It looks like I re-released my managed ObjectContext; I originally released it both in TableViewControllers in dealloc, and the third time I went between two controllers (Story → Sentence → Story → Sentence → Story → Crash). Some debugging showed that I crash in my delegate delet after this code in the ViewDidLoad of both TableViewControllers:

 if (managedObjectContext == nil) 
{ 
    managedObjectContext = [(StoryBotAppDelegate *)[[UIApplication sharedApplication] delegate] managedObjectContext];
    NSLog(@"After managedObjectContext: %@",  managedObjectContext);
}

A few more studies found this discussion , which made me believe that this was the case with the released ManagedObjectContext:

The second more prosaic issue is the simply overridden NSManagedObject. Tools The ObjectAlloc tool should be able to help you.

So, I deleted [managedObjectContext release]; from my dealloc to TableViewController, and now I have no leaks (according to the tools) and without failures.

It seems the problem is fixed, but here is the question:

• Perhaps I don’t have a point at all, and I'm just hiding another problem. How can I find a redundant release or a real problem?

• If I fixed the problem, I would like to know why it is fixed and why I do not need to free MOC in the second TableViewController

MakeSentenceTableViewController.m

@implementation MakeSentenceTableViewController
@synthesize story, managedObjectContext;
- (void)viewDidLoad {
[super viewDidLoad];

self.title = @"My Story";
NSLog(@"Passed Story Object: %@", story);
if (managedObjectContext == nil) 
{ 
    NSLog(@"managedObjectContext == nil");
    managedObjectContext = [(StoryBotAppDelegate *)[[UIApplication sharedApplication] delegate] managedObjectContext];
    NSLog(@"After managedObjectContext: %@",  managedObjectContext);
}else{
    NSLog(@"managedObjectContext != nil");
}
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Sentence" inManagedObjectContext:managedObjectContext];
[request setEntity:entity];

//sorting stuff:
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"order" ascending: YES];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects: sortDescriptor, nil];
[request setSortDescriptors:sortDescriptors];
//[request setFetchBatchSize:FETCH_BATCH_SIZE];
[sortDescriptors release];
[sortDescriptor release];

 fetchedResultsController = [[NSFetchedResultsController alloc] 
                            initWithFetchRequest:request managedObjectContext:managedObjectContext 
                            sectionNameKeyPath:nil cacheName:nil];
[request release];

NSError *error;
[fetchedResultsController performFetch:&error];

NSLog(@"FetchedResultsController: %@", fetchedResultsController);
NSLog(@"fetchedResultsController RetainCount at viewDidLoad: %d",     [fetchedResultsController retainCount]);
 }
//snip...table view bits
- (void)dealloc {
[fetchedResultsController release];
//Why don't I have to release this?
//[managedObjectContext release];
    [super dealloc];
}

Answer 1

. "MOC" (), , . , self.managedObjectContext =... ( ), [self setManagedObjectContext:...], dealloc, , "MOC" , .