Why won't my model save to Core Data? - ios

Question

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?

Answer 1

You should save the context in order to save in the persistent store.
NSError *error;
[context save:&error];
Hope it helps. Cheers