Error in iPhone core data - iphone

Question

My AppDelegate.h:
#import <UIKit/UIKit.h>
#import "Child.h"
#interface AppDelegate : UIResponder <UIApplicationDelegate> {
NSManagedObjectModel *managedObjectModel;
NSManagedObjectContext *managedObjectContext;
NSPersistentStoreCoordinator *persistentStoreCoordinator;
}
#property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext;
#property (readonly, retain, nonatomic) NSManagedObjectModel *managedObjectModel;
#property (readonly, strong, nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator;
- (NSString *)applicationDocumentsDirectory;
#property (strong, nonatomic) UIWindow *window;
#end
AppDelegate.m:
#import "AppDelegate.h"
#implementation AppDelegate
#synthesize managedObjectContext = __managedObjectContext;
#synthesize managedObjectModel = __managedObjectModel;
#synthesize persistentStoreCoordinator = __persistentStoreCoordinator;
#synthesize window = _window;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Override point for customization after application launch.
NSManagedObjectContext *context = [self managedObjectContext];
if (!context) {
NSLog(#"Error");
}
return YES;
}
- (void)applicationWillTerminate:(UIApplication *)application { /* Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:. */
NSError *error;
if (managedObjectContext != nil) {
if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {
// Handle the error.
}
}
}
// Explicitly write Core Data accessors
- (NSManagedObjectContext *) managedObjectContext {
if (managedObjectContext != nil) {
return managedObjectContext;
}
NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (coordinator != nil) {
managedObjectContext = [[NSManagedObjectContext alloc] init];
[managedObjectContext setPersistentStoreCoordinator: coordinator];
}
return managedObjectContext;
}
- (NSManagedObjectModel *)managedObjectModel {
if (managedObjectModel != nil) {
return managedObjectModel;
}
managedObjectModel = [NSManagedObjectModel mergedModelFromBundles:nil];
return managedObjectModel;
}
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {
if (persistentStoreCoordinator != nil) {
return persistentStoreCoordinator;
}
NSURL *storeUrl = [NSURL fileURLWithPath: [[self applicationDocumentsDirectory] stringByAppendingPathComponent: #"iSalahProject.sqlite"]];
NSError *error = nil;
persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
if(![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeUrl options:nil error:&error]) {
/*Error for store creation should be handled in here*/
}
return persistentStoreCoordinator;
}
- (NSString *)applicationDocumentsDirectory {
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *basePath = ([paths count] > 0) ? [paths objectAtIndex:0] : nil;
return basePath;
}
#end
My controller implementation class where entity is being created and I am getting the error:
-(IBAction)addChildren:(id)sender{
inputChildName = nameOfChild.text;
NSManagedObjectContext *context = [app managedObjectContext];
Child * childrenName = [NSEntityDescription insertNewObjectForEntityForName:#"Child" inManagedObjectContext:context];
childrenName.name = inputChildName;
}
The error I am getting is:
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '+entityForName: could not locate an NSManagedObjectModel for entity name 'Child''
I am using iOS-5 XCode 4.2 ARC. Please help me resolving this issue, I already have spent hours resolving it, but I couldn't find any solutions.

Answer 1

Your application is terminating because your managedObjectContext is nil. Check for it and if its nil copy it from delegate. You can use this if condition in your -(IBAction)addChildren:(id)sender method
if (managedObjectContext == nil)
{
managedObjectContext = [(CoreDataBooksAppDelegate *)[[UIApplication sharedApplication] delegate] managedObjectContext];
NSLog(#"After managedObjectContext: %#", managedObjectContext);
}

Answer 2

Following are the possibilities for this error to occur:
Typo in the Entity name.
Nil managed object context object.
Failure to add the model containing the entity to the persistent
store the context uses.
Failure to add the correct persistent store to the context itself.