Please check the enity name and also do the following
in YourAppDeleagte.h
+(YourAppDeleagte*)sharedManagedContext;
in YourAppDeleagte.m
+(YourAppDeleagte*)sharedManagedContext{
return (YourAppDeleagte *)[[UIApplication sharedApplication]delegate];
}
in viewController.m
#import "YourAppDelegate.h"
@property(nonatomic,retain)NSmanagedObjectContext *managedObjectContext;
-(void)viewDidLoad{
[super viewDidLoad];
self.managedObjectContext=[YourAppDelagete shareManagedContext].managedObjectContext;
}