Question

i have a core data database that start from the AppDelegate, and there i’ll do this:

MasterViewController *masterViewController = [[[MasterViewController alloc] initWithNibName:@"MasterViewController" bundle:nil] autorelease];

masterViewController.managedObjectContext = self.managedObjectContext;

so in this way i can access to the database in the master view, then i want access to the core data in other classes, and i do this:

id delegateContext = [[UIApplication sharedApplication] delegate];

NSManagedObjectContext *context = [delegateContext managedObjectContext];

but when i add, and access the information, i have some bad Exc access and other error in various part of the code when i try to access to the information of the database, so i think that maybe i have used in bad way the core data, to access the information from other classes.

maybe i have to release the delegatecontext?…i haven’t release it in any class i have used it, and if i have release it, where i have do it?

anyone can help me?

Answer 1

Problem is you are taking delegateContext of type id instead of NSManagedObjectContext and assigning it to *contextin these two lines.

id delegateContext = [[UIApplication sharedApplication] delegate];
NSManagedObjectContext *context = [delegateContext managedObjectContext]; 

How about adding these lines whenever you need to save or access managedObjectContext, check it if its nil if YES copy it from Appdelegate.

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

Just try to remove your these two lines and add the above if condition I am suggesting. Should work.

Update 1: As you are asking I am mentioning steps for creating
Appdelegate’s instance to access global properties.

      #import "AppDelegate.h"

after @implementation create instance of Appdelegate

      AppDelegate *app;

in viewDidLoad method…

      app=(AppDelegate *)[[UIApplication sharedApplication]delegate];