An NSManagedObject of class 'NSManagedObject' must have a valid NSEntityDescription - ios

I am working on Objective-C with CoreData, i am getting below error...
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'An NSManagedObject of class
'NSManagedObject' must have a valid NSEntityDescription.'
I added CoreData to my project. I created saveData method in viewControllerA and i called it in viewControllerB.
In this scenario I am getting error, if I call saveData method in viewDidLoad of viewControllerA it's working properly.
In AppDelegate.h
#property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext;
#property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel;
#property (readonly, strong, nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator;
In AppDelegate.m
#pragma mark - Core Data stack
#synthesize managedObjectContext = _managedObjectContext;
#synthesize managedObjectModel = _managedObjectModel;
#synthesize persistentStoreCoordinator = _persistentStoreCoordinator;
- (NSURL *)applicationDocumentsDirectory {
// The directory the application uses to store the Core Data store file. This code uses a directory named "com.brninfotech._607_introToCoreDataFinal" in the application's documents directory.
return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}
- (NSManagedObjectModel *)managedObjectModel {
// The managed object model for the application. It is a fatal error for the application not to be able to find and load its model.
if (_managedObjectModel != nil) {
return _managedObjectModel;
}
NSURL *modelURL = [[NSBundle mainBundle] URLForResource:#"VehicleNumberDataBase" withExtension:#"momd"];
_managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
return _managedObjectModel;
}
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {
// The persistent store coordinator for the application. This implementation creates and returns a coordinator, having added the store for the application to it.
if (_persistentStoreCoordinator != nil) {
return _persistentStoreCoordinator;
}
// Create the coordinator and store
_persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:#"VehicleNumberDataBase.sqlite"];
// NSLog(#"StoreURL is %#",storeURL);
NSError *error = nil;
NSString *failureReason = #"There was an error creating or loading the application's saved data.";
if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
// Report any error we got.
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
dict[NSLocalizedDescriptionKey] = #"Failed to initialize the application's saved data";
dict[NSLocalizedFailureReasonErrorKey] = failureReason;
dict[NSUnderlyingErrorKey] = error;
error = [NSError errorWithDomain:#"YOUR_ERROR_DOMAIN" code:9999 userInfo:dict];
// Replace this with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
return _persistentStoreCoordinator;
}
- (NSManagedObjectContext *)managedObjectContext {
// Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.)
if (_managedObjectContext != nil) {
return _managedObjectContext;
}
NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (!coordinator) {
return nil;
}
_managedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
[_managedObjectContext setPersistentStoreCoordinator:coordinator];
return _managedObjectContext;
}
#pragma mark - Core Data Saving support
- (void)saveContext {
NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
if (managedObjectContext != nil) {
NSError *error = nil;
if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {
// Replace this implementation with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
}
}
in viewControllerA viewDidLoad
self.ad = (AppDelegate *)[[UIApplication sharedApplication]delegate];
self.VehicleNumberED = [NSEntityDescription entityForName:#"VehicleNumberEntity" inManagedObjectContext:self.ad.managedObjectContext];
- (void)saveData {
NSManagedObject * managedObj = [[NSManagedObject alloc]initWithEntity:self.VehicleNumberED insertIntoManagedObjectContext:self.ad.managedObjectContext];
[managedObj setValue:self.textFieldString forKey:#"vehicleNumberAtt"];
NSError * errorObj;
[self.ad.managedObjectContext save:&errorObj];
if (errorObj) {
NSLog(#"Something goes wrong");
}else {
NSLog(#"Saved Successfully");
}
NSFetchRequest * fetReq = [NSFetchRequest fetchRequestWithEntityName:#"VehicleNumberEntity"];
NSError * fetchErrorObj;
self.storedDataArray = [self.ad.managedObjectContext executeFetchRequest:fetReq error:&fetchErrorObj];
NSLog(#"array count is %lu", self.storedDataArray.count);
for (int i=0; i<self.storedDataArray.count; i++) {
self.storedManagedObj = [self.storedDataArray objectAtIndex:i];
self.vehicleNumberArray = [self.storedManagedObj valueForKey:#"vehicleNumberAtt"];
}
NSLog(#"Vehicle number is : %#", [self.storedManagedObj valueForKey:#"vehicleNumberAtt"]);
}
in ViewVontrollerB
- (IBAction)saveVehicleNumberButton:(UIButton *)sender {
VehicleDetailsViewController *vedvc = [[VehicleDetailsViewController alloc]init];
vedvc = [self.storyboard instantiateViewControllerWithIdentifier:#"VeDVC"];
vedvc.textFieldString = self.vehicleNumberTextField.text;
[vedvc saveData];
[self.navigationController pushViewController:vedvc animated:YES];
}

The issue here is that you are executing [vedvc saveData] before displaying the vedvc view controller. At this point, vedvc has not been displayed, so its viewDidLoad has not yet been executed. Consequently self.ad and self.VehicleNumberED are both nil. Hence the error: the entity description is nil.
The simplest fix would be to move the initialisation of those two variables (ad and VehicleNumberED) to the saveData method. But you might do better to rethink your code structure.

Related

Enabling Core data into existing Project does not work

I have created a Project in Xcode 5.1.1 without core data support.
Now i am trying to get the core data support.
Steps:
1) File -> New -> File -> Data Model -> Added.
It created : samplecd.xcdatamodeld
2) Added Entity:
myname type: String
3)
To do the changes in the AppDelegate.h and AppDelegate.m,
I have created one more project with 'core data' enabled, and copied
the below contents into the previous project.
AppDelegate.h
#property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext;
#property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel;
#property (readonly, strong, nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator;
- (void)saveContext;
- (NSURL *)applicationDocumentsDirectory;
AppDelegate.m
- (void)saveContext
{
NSError *error = nil;
NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
if (managedObjectContext != nil) {
if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
}
}
#pragma mark - Core Data stack
// Returns the managed object context for the application.
// If the context doesn't already exist, it is created and bound to the persistent store coordinator for the application.
- (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:#"withcoredata" withExtension:#"momd"];
_managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
return _managedObjectModel;
}
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
if (_persistentStoreCoordinator != nil) {
return _persistentStoreCoordinator;
}
NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:#"withcoredata.sqlite"];
NSError *error = nil;
_persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
return _persistentStoreCoordinator;
}
#pragma mark - Application's Documents directory
// Returns the URL to the application's Documents directory.
- (NSURL *)applicationDocumentsDirectory
{
return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}
ERROR:
I get the below compilation error:
"AppDelegate.m:122:35: Receiver 'NSManagedObjectContext' for class message is a forward declaration"
AppDelegate.m:122:34: Receiver type 'NSManagedObjectContext' for instance message is a forward declaration
How to solve this issue?
your core data model name is samplecd and your sqlite database name is withcoredata
both name should be similar for using core data in existing project.
Change the name and let me know if your problem is solved or not.
You need to import CoreData/CoreData.h in your AppDelegte.h file:
#import <CoreData/CoreData.h>
and in YourApp-Prefix.pch:
#ifdef __OBJC__
#import <UIKit/UIKit.h>
#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>
#endif

Why won't my model save to Core Data?

I'm quite new to Objective-C and I'm trying to mess around with Core Data. I have the following App Delegate interface and implementation:
#import <UIKit/UIKit.h>
#interface SDTAppDelegate : UIResponder <UIApplicationDelegate>
#property (strong, nonatomic) UIWindow *window;
#property (nonatomic, strong) NSManagedObjectContext *managedObjectContext;
#property (nonatomic, strong) NSManagedObjectModel *managedObjectModel;
#property (nonatomic, strong) NSPersistentStoreCoordinator *persistentStoreCoordinator;
- (void)saveManagedObjectContext;
- (NSManagedObjectContext *)setupManagedObjectContext;
- (NSManagedObjectModel *)setupManagedObjectModel;
- (NSPersistentStoreCoordinator *)setupPersistentStoreCoordinator;
- (NSURL *)applicationDocumentsDirectory;
#end
Implementation
#import "SDTAppDelegate.h"
#import "ToDoItem.h"
#implementation SDTAppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
// Get the managed object context and associate it to the app delegate
self.managedObjectContext = [self setupManagedObjectContext];
return YES;
}
- (void)applicationWillTerminate:(UIApplication *)application
{
[self saveManagedObjectContext];
}
/**
* Save the MOC!
*/
- (void)saveManagedObjectContext
{
NSError *error = nil;
if (self.managedObjectContext != nil)
{
if ([self.managedObjectContext hasChanges] && ![self.managedObjectContext save:&error])
{
/*
THIS NEEDS TO BE REPLACED
*/
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
}
}
#pragma mark - Core Data stack
/**
Returns the managed object context for the application.
If the context doesn't already exist, it is created and bound to the persistent store coordinator for the application.
*/
- (NSManagedObjectContext *)setupManagedObjectContext
{
if (self.managedObjectContext != nil)
{
return self.managedObjectContext;
}
NSPersistentStoreCoordinator *coordinator = [self setupPersistentStoreCoordinator];
if (coordinator != nil)
{
self.managedObjectContext = [[NSManagedObjectContext alloc] init];
[self.managedObjectContext setPersistentStoreCoordinator:coordinator];
}
return self.managedObjectContext;
}
/**
* Return the managed object model. If it doesn't exist, create it.
*/
- (NSManagedObjectModel *)setupManagedObjectModel
{
if (self.managedObjectModel != nil)
{
return self.managedObjectModel;
}
NSURL *modelURL = [[NSBundle mainBundle] URLForResource:#"Model" withExtension:#"momd"];
self.managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
return self.managedObjectModel;
}
/**
* Return the persistent store coordinator. If it doesn't exist, create it.
*/
- (NSPersistentStoreCoordinator *)setupPersistentStoreCoordinator
{
if (self.persistentStoreCoordinator != nil)
{
return self.persistentStoreCoordinator;
}
NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:#"Model.sqlite"];
NSError *error = nil;
self.persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self setupManagedObjectModel]];
if (![self.persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType
configuration:nil
URL:storeURL
options:nil
error:&error])
{
/*
THIS NEEDS TO BE REPLACED
*/
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
return self.persistentStoreCoordinator;
}
#pragma mark - Application's Documents directory
/**
* Return the URL to the application's Documents directory.
*/
- (NSURL *)applicationDocumentsDirectory
{
return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}
#end
And then in my controller I have the following to save a new model:
// Take the managed object context from the app delegate
SDTAppDelegate *appDelegate = (SDTAppDelegate *)[UIApplication sharedApplication].delegate;
NSManagedObjectContext *context = appDelegate.managedObjectContext;
// Add the new item
ToDoItem *newItem = [NSEntityDescription insertNewObjectForEntityForName:#"ToDoItem" inManagedObjectContext:context];
newItem.item = self.textField.text;
newItem.completed = 0;
No matter what happens I can't get the application to save. It shows up fine in the interface, but when I quit and restart the data is no longer there. I'm guessing this is something wrong with my persistent storage?
You should save the context in order to save in the persistent store.
NSError *error;
[context save:&error];
Hope it helps. Cheers

SIGABRT when saving to managed object context in core data

This code is supposed to save my data to core data in TestViewController.m file:
//Property
#property (nonatomic, retain) NSManagedObjectContext *managedObjectContext;
//Methods
- (void)saveUser:(NSString *) username withEmail:(NSString *) email withName:(NSString *) name
{
//1
AppDelegate* appDelegate = [UIApplication sharedApplication].delegate;
//2
self.managedObjectContext = appDelegate.managedObjectContext;
User *coreDataUser = [NSEntityDescription insertNewObjectForEntityForName:#"User" inManagedObjectContext:self.managedObjectContext];
coreDataUser.username = username;
coreDataUser.email = email;
coreDataUser.name = name;
NSError *error;
if (![self.managedObjectContext save:&error])
{
NSLog(#"Whoops, couldn't save: %#", [error localizedDescription]);
}
}
//In my save user method I have stuff that is done in another thread but then this is called:
// Add in any UIKit code here on main queue
dispatch_async(dispatch_get_main_queue(), ^{
if (isUnique == YES)
{
[self saveUser:[emailStr lowercaseString] withEmail:emailStr withName:nameStr];
My code always crashes on:
ser *coreDataUser = [NSEntityDescription insertNewObjectForEntityForName:#"User" inManagedObjectContext:self.managedObjectContext];
It says signal SIGABRT in main.
I am following this tutorial: http://www.codigator.com/tutorials/ios-core-data-tutorial-with-example/
And running in ios 7.
What am I missing?
I'm tracing the appDelegate.m code now but it looks like this:
// 1
- (NSManagedObjectContext *) managedObjectContext {
if (_managedObjectContext != nil) {
return _managedObjectContext;
}
NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (coordinator != nil) {
_ managedObjectContext = [[NSManagedObjectContext alloc] init];
[_managedObjectContext setPersistentStoreCoordinator: coordinator];
}
return _managedObjectContext;
}
//2
- (NSManagedObjectModel *)managedObjectModel {
if (_managedObjectModel != nil) {
return _managedObjectModel;
}
_managedObjectModel = [NSManagedObjectModel mergedModelFromBundles:nil];
return _managedObjectModel;
}
//3
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
if (_persistentStoreCoordinator != nil)
{
return _persistentStoreCoordinator;
}
NSString *test = [self applicationDocumentsDirectory];
NSString *test2 = test;
NSURL *storeUrl = [NSURL fileURLWithPath: [[self applicationDocumentsDirectory] stringByAppendingPathComponent: #"HappyPeople.sqlite"]];
NSError *error = nil;
_persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
i f (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeUrl options:nil error:&error])
{
/*Error for store creation should be handled in here*/
}
return _persistentStoreCoordinator;
}
- (NSString *)applicationDocumentsDirectory
{
return [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
}
Seems like the sqllite db file gets created.
The exception I am getting is this:
NSException * name:#"NSInternalInconsistencyException" reason:#"+entityForName: could not locate an entity named 'Users' in this model." 0x0895ee20
I know this question is a little old...
This is the exception I get when I change the schema of the object model and try to use a file with the old schema. The sqllite db on disk may not match your apps schema.
I have been using CoreData with a UIManagedDocument so it is a little different. There you have options to automatically migrate on the open.
Also, early on in the comments it was asked whether the ManagedObjectContext was nil. I believe that this should be checked before you call the insert. Are we sure all of the core data setup is on the main queue? It can take a little time to open. (Again with UIManagedDocument is explicitly on another thread.)

Core Data - NSInvalidArgumentException

there's not much to say, i have done another application for core data everything went always fine.
This application is giving a weird error.
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+entityForName: nil is not a legal NSManagedObjectContext parameter searching for entity name 'Ingredient''
*** First throw call stack:(0x1faa012 0x13e7e7e 0x10edf57 0x1134052 0x3211 0x11a04b 0x2fe2 0x22c1 0x19157 0x19747 0x1a94b 0x2bcb5 0x2cbeb 0x1e698 0x1f05df9 0x1f05ad0 0x1f1fbf5 0x1f1f962 0x1f50bb6 0x1f4ff44 0x1f4fe1b 0x1a17a 0x1bffc 0x20dd 0x2005)
vlibc++abi.dylib: terminate called throwing an exception
i tried to simplify my app using only the app delegate and a mainViewController, in the MainViewController i tried to add an pbject to my Coredata just to see if everithing is working. This is my model
App delegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
MasterViewController *masterViewController = [[MasterViewController alloc]initWithNibName:#"MasterViewController" bundle:nil];
masterViewController.managedObjectContext = self.managedObjectContext;
[self.window setRootViewController:masterViewController];
self.window.backgroundColor = [UIColor whiteColor];
[self.window makeKeyAndVisible];
return YES;
}
- (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:#"pizzaCoreData" withExtension:#"momd"];
_managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
return _managedObjectModel;
}
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
if (_persistentStoreCoordinator != nil) {
return _persistentStoreCoordinator;
}
NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:#"pizzaCoreData.sqlite"];
NSError *error = nil;
_persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
/*
Replace this implementation with code to handle the error appropriately.
abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
Typical reasons for an error here include:
* The persistent store is not accessible;
* The schema for the persistent store is incompatible with current managed object model.
Check the error message to determine what the actual problem was.
If the persistent store is not accessible, there is typically something wrong with the file path. Often, a file URL is pointing into the application's resources directory instead of a writeable directory.
If you encounter schema incompatibility errors during development, you can reduce their frequency by:
* Simply deleting the existing store:
[[NSFileManager defaultManager] removeItemAtURL:storeURL error:nil]
* Performing automatic lightweight migration by passing the following dictionary as the options parameter:
#{NSMigratePersistentStoresAutomaticallyOption:#YES, NSInferMappingModelAutomaticallyOption:#YES}
Lightweight migration will only work for a limited set of schema changes; consult "Core Data Model Versioning and Data Migration Programming Guide" for details.
*/
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
return _persistentStoreCoordinator;
}
- (NSURL *)applicationDocumentsDirectory
{
return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}
MainViewController
- (void)viewDidLoad
{
[super viewDidLoad];
TableIngredientsViewController *tableIngredientVC = [[TableIngredientsViewController alloc]init];
TablePizzasViewController *tablePizzaVC = [[TablePizzasViewController alloc]init];
NSManagedObject *newPizza = [NSEntityDescription insertNewObjectForEntityForName:#"Ingredient" inManagedObjectContext:_managedObjectContext];
[newPizza setValue:#"TIMIDA" forKey:#"name"];
NSError *error;
if (![_managedObjectContext save:&error]){
NSLog(#"Error %# %#", error, [error userInfo]);
}
UINavigationController *ingredientNavController = [[UINavigationController alloc]initWithRootViewController:tableIngredientVC];
UINavigationController *pizzaNavController = [[UINavigationController alloc]initWithRootViewController:tablePizzaVC];
[self setViewControllers:#[pizzaNavController, ingredientNavController]];
}
This is a screenshot of the model:
http://tinypic.com/view.php?pic=97nrcn&s=5
i have updated my AppDelegate, i forgot copy last methods
Your _managedObjectContext is nil when you are doing this
NSManagedObject *newPizza = [NSEntityDescription insertNewObjectForEntityForName:#"Ingredient" inManagedObjectContext:_managedObjectContext];
So before passing your context to a view controller make sure it is initialized properly.
You have to take your managedObjectContext from your appDelegate. So in your MainController instead of:
_managedObjectContext
use:
((AppDelegate *)[[UIApplication sharedApplication] delegate]).managedObjectContext

Core data entity array generate crash on release or remove objects in IOS

This is my CoreDataManagerClass.
#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>
#interface RTC_CoreDataManager : NSObject
#property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext;
#property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel;
#property (readonly, strong, nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator;
- (void)saveContext;
- (NSURL *)applicationDocumentsDirectory;
-(void)insertEntity:(NSString *)entityName arrayOfManagedObject:(NSMutableArray *)array;
+(RTC_CoreDataManager *)shredInstance;
#end
#import "RTC_CoreDataManager.h"
RTC_CoreDataManager *obj_RTC;
#implementation RTC_CoreDataManager
#synthesize managedObjectContext = __managedObjectContext;
#synthesize managedObjectModel = __managedObjectModel;
#synthesize persistentStoreCoordinator = __persistentStoreCoordinator;
- (void)saveContext
{
NSError *error = nil;
NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
if (managedObjectContext != nil) {
if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
}
}
+(RTC_CoreDataManager *)shredInstance{
if (obj_RTC == nil) {
obj_RTC = [[RTC_CoreDataManager alloc]init];
}
return obj_RTC;
}
#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:#"RTC" withExtension:#"momd"];
__managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
return __managedObjectModel;
}
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
if (__persistentStoreCoordinator != nil) {
return __persistentStoreCoordinator;
}
NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:#"RTC.sqlite"];
NSError *error = nil;
if (![[NSFileManager defaultManager] copyItemAtURL:storeURL toURL:[NSURL alloc] error:&error]) {
NSLog(#"Oops, could copy preloaded data");
}
__persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
if (![__persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
return __persistentStoreCoordinator;
}
#pragma mark - Application's Documents directory
// Returns the URL to the application's Documents directory.
- (NSURL *)applicationDocumentsDirectory
{
return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}
-(void)insertEntity:(NSString *)entityName arrayOfManagedObject:(NSMutableArray *)array
{
NSManagedObjectContext *backgroundMOC = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
for (id object in array)
{
[backgroundMOC performBlockAndWait:^
{
NSError *error;
if (![__managedObjectContext save:&error])
{
NSLog(#"Whoops, couldn't save: %#", [error localizedDescription]);
}
}];
}
}
#end
And this is my code in another controller.
-(void)viewDidLoad
{
[super viewDidLoad];
appDele_Obj = (RTC_AppDelegate *)[[UIApplication sharedApplication] delegate];
appDele_Obj.entityArray=[[NSMutableArray alloc]init];
for (int i=0; i<10; i++)
{
Survey *objSurvey = [NSEntityDescription
insertNewObjectForEntityForName:#"Survey"
inManagedObjectContext:[RTC_CoreDataManager shredInstance].managedObjectContext]; [objSurvey setFirstName:#"1"];
[objSurvey setLastName:#"2"];
[objSurvey setEmpId:#"3"];
[objSurvey setLanguage:#"Hindi"];
[objSurvey setCountry:#"India"];
[objSurvey setSurveyNo:[NSNumber numberWithInt:2]];
[[appDele_Obj entityArray] addObject:objSurvey];
[objSurvey release];
}
//[objSurvey release];
[[RTC_CoreDataManager shredInstance] insertEntity:#"Survey" arrayOfManagedObject:[appDele_Obj entityArray]];
if ([[appDele_Obj entityArray]count] >0) {
[[appDele_Obj entityArray] removeAllObjects];
}
}
So My question is,
If I call method removeAllObjects on [appDele_Obj entityArray] crashing the application. Why I can not call [[appDele_Obj entityArray] removeAllObjects];
in above approach. Any one can help me to solve this crash.
Thanks.
It's a simple case of memory mis-management. This creates an autoreleased object:
Survey *objSurvey = [NSEntityDescription
insertNewObjectForEntityForName:#"Survey"
inManagedObjectContext:[RTC_CoreDataManager shredInstance].managedObjectContext];
Then you do this:
[[appDele_Obj entityArray] addObject:objSurvey];
[objSurvey release];
You should not be calling release here. The object is autoreleased-- calling release is not only unnecessary, it's dangerous. Later on when you remove the objects from the array, you end up over-releasing every object in it. That causes the crash.
A few other things from the code:
Calling save: on a managed object context in a loop is unnecessary unless you're making new changes on each pass through the loop. Your insertEntity:arrayOfManagedObject: method is doing a lot of unnecessary work.
The array in viewDidLoad is not necessary or useful for what you're doing. You've created the objects, and they're in the managed object context. Once you finish setting the attributes of those objects, you don't need to keep references. Keep adding objects until you're done, then tell the managed object context to save.
It's a minor detail, but you named a method that creates a singleton shredInstance. "Shred" is almost exactly the opposite of what you're doing in that method. You probably meant sharedInstance.

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