+entityForName: nil is not a legal NSManagedObjectContext parameter searching for entity name 'Account''
Solution 1
- (NSManagedObjectContext *)managedObjectContext
{
if (managedObjectContext != nil) return managedObjectContext;
NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (coordinator != nil) {
managedObjectContext = [[NSManagedObjectContext alloc] init];
[managedObjectContext setPersistentStoreCoordinator:coordinator];
}
return managedObjectContext;
}
- You haven't provided a lazy loading implementation of
persistentStoreCoordinator
- so
coordinator
will always benil
- so you will always be returning
nil
from this method - which means you will always get the error above.
To explain the error:
+entityForName: nil is not a legal NSManagedObjectContext parameter searching for entity name 'Account'
It's not immediately obvious from reading it, but this means that nil
is not a legal thing to pass for the managed object context. On first reading, it looks like you're doing entityForName:nil
but that isn't the case.
To fix the problem, you will need to provide a valid persistent store coordinator. I have a small article here which explains just how little code you need to set up a core data stack, this may help you.
Solution 2
In my case, I'm using multiple contexts (parent/child) with different concurrency types to improve performance. I have three contexts:
-
storeContext
which is the only context whosepersistentStoreCoordinator
had been set. -
viewContext
whose parent isstoreContext
-
backgroundContext
whose parent should have beenviewContext
but I forgot to setbackgroundContext.parent = viewContext
.
Saving an entity on the backgroundContext
produced the same error...
+entityForName: nil is not a legal NSManagedObjectContext parameter searching for entity name...
...because backgroundContext
wasn't a part of the parent/child context chain.
Setting backgroundContext
's parent
to viewContext
established the chain back to the persistent store coordinator and resolved the error.
ferrojr
Updated on May 15, 2020Comments
-
ferrojr about 4 years
I have tried a lot of options, but can't find the solution for this problem. I created a Core Data file and named the entity Account, Created an string attribute called username. Then edited the class of the entity to NSManagedObject, not sure if this is right. Now, the following code is in my LoginViewController:
- (void)viewDidLoad { [super viewDidLoad]; ITAppDelegate *appDelegate = (ITAppDelegate *)[[UIApplication sharedApplication] delegate]; NSManagedObjectContext *context = appDelegate.managedObjectContext; Account *newAccount = [NSEntityDescription insertNewObjectForEntityForName:@"Account" inManagedObjectContext:context]; [newAccount setValue:@"Jorge" forKey:@"username"]; [newAccount setPassword:@"password"]; NSLog(@"username:%@ password: %@", [newAccount username], [newAccount password]); }
I followed This Tutorial and my code files look like this:
ITAppDelegate.h
#import <UIKit/UIKit.h> @interface ITAppDelegate : UIResponder <UIApplicationDelegate> @property (strong, nonatomic) UIWindow *window; @property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext; @property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel; @property (readonly, strong, nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator; @end
ITAppDelegate.m
#import "ITAppDelegate.h" #import "LoginViewController.h" @implementation ITAppDelegate @synthesize managedObjectContext = _managedObjectContext; @synthesize persistentStoreCoordinator = _persistentStoreCoordinator; @synthesize managedObjectModel = _managedObjectModel; - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { // Override point for customization after application launch. return YES; } #pragma mark - Core Data stack - (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; } NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"Model" withExtension:@"momd"]; _managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL]; return _managedObjectModel; } - (NSPersistentStoreCoordinator *)persistentStoreCoordinator { if (_persistentStoreCoordinator != nil) { return _persistentStoreCoordinator; } return _persistentStoreCoordinator; } @end
AccountBase.h
#import <UIKit/UIKit.h> #import <CoreData/CoreData.h> @interface AccountBase : NSManagedObject @property (nonatomic, retain) NSString *username; @end
AccountBase.m
#import "AccountBase.h" @implementation AccountBase @dynamic username; @end
Account.h
#import "AccountBase.h" #import <CoreData/CoreData.h> @interface Account : AccountBase @property (nonatomic, assign) NSString *password; @end
Account.m
#import "Account.h" #import "KeychainHelper.h" @implementation Account - (NSString*)password { if (self.username) return [KeychainHelper getPasswordForKey:self.username]; return nil; } - (void)setPassword:(NSString*)aPassword { if (self.username) [KeychainHelper setPassword:aPassword forKey:self.username]; } - (void)prepareForDeletion { if (self.username) [KeychainHelper removePasswordForKey:self.username]; } @end
KeychainHelper.h
#import <Foundation/Foundation.h> @interface KeychainHelper : NSObject + (NSString*)getPasswordForKey:(NSString*)aKey; + (void)setPassword:(NSString*)aPassword forKey:(NSString*)aKey; + (void)removePasswordForKey:(NSString*)aKey; @end
KeychainHelper.m
#import "KeychainHelper.h" #import <Security/Security.h> @interface KeychainHelper () + (NSMutableDictionary*)dictionaryForKey:(NSString*)aKey; @end @implementation KeychainHelper static const NSString *ironTrainers = @"com.domain.myapplication"; + (NSMutableDictionary*)dictionaryForKey:(NSString*)aKey { NSData *encodedKey = [aKey dataUsingEncoding:NSUTF8StringEncoding]; NSMutableDictionary *searchDictionary = [NSMutableDictionary dictionary]; [searchDictionary setObject:(__bridge id)kSecClassGenericPassword forKey:(__bridge id)kSecClass]; [searchDictionary setObject:encodedKey forKey:(__bridge id)kSecAttrGeneric]; [searchDictionary setObject:encodedKey forKey:(__bridge id)kSecAttrAccount]; [searchDictionary setObject:ironTrainers forKey:(__bridge id)kSecAttrService]; return searchDictionary; } + (NSString*)getPasswordForKey:(NSString*)aKey { NSString *password = nil; NSMutableDictionary *searchDictionary = [self dictionaryForKey:aKey]; [searchDictionary setObject:(__bridge id)kSecMatchLimitOne forKey:(__bridge id)kSecMatchLimit]; [searchDictionary setObject:(id)kCFBooleanTrue forKey:(__bridge id)kSecReturnData]; CFTypeRef result = NULL; BOOL statusCode = SecItemCopyMatching((__bridge CFDictionaryRef)searchDictionary, &result); if (statusCode == errSecSuccess) { NSData *resultData = CFBridgingRelease(result); password = [[NSString alloc] initWithData:resultData encoding:NSUTF8StringEncoding]; } return (__bridge NSString *)(result); } + (void)removePasswordForKey:(NSString*)aKey { NSMutableDictionary *keyDictionary = [self dictionaryForKey:aKey]; SecItemDelete((__bridge CFDictionaryRef)keyDictionary); } + (void)setPassword:(NSString*)aPassword forKey:(NSString*)aKey { [KeychainHelper removePasswordForKey:aKey]; NSData *encodedPassword = [aPassword dataUsingEncoding:NSUTF8StringEncoding]; NSMutableDictionary *keyDictionary = [self dictionaryForKey:aKey]; [keyDictionary setObject:encodedPassword forKey:(__bridge id)kSecValueData]; SecItemAdd((__bridge CFDictionaryRef)keyDictionary, nil); } @end
Any help appreciated. Thanks.
-
jrturton over 10 yearsThe error message states that the managedObjectContext parameter is nil, this is nothing to do with the model
-
ferrojr over 10 yearsThanks, it worked for the username. I changed app delegate (please see above), but now Im getting the error: -[NSManagedObject setPassword:]: unrecognized selector sent to instance
-
jrturton over 10 yearsWell, that's a whole different question. That looks like you haven't defined the proper subclass in your data model (there's a "Name" and "Class" box to fill in)
-
ferrojr over 10 yearsMy data model has one attribute which is username. And the entity name is Account, the class that shows there is NSManagedObject, which I edited earlier, not sure if that's right though.
-
jrturton over 10 yearsYou have to set the class to Account and generate the Account.h and Account.m files by selecting the entity and choosing editor --> create NSManagedObject subclass..
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ferrojr over 10 yearsThis is my output: username:Jorge password: <70617373 776f7264> I'm guessing it worked, right?