On Feb 20, 2011, at 10:23 PM, Shane wrote:
...
Shane,
you usually need these initial steps for virtually any Core Data application:
(please refer to corresponding documentation for each CoreData class and method
mentioned!)
@interface SomeDelegateOrControllerOrElse (CoreDataAdditions) {
NSManagedObjectContext* managedObjectContext_;
NSManagedObjectModel* managedObjectModel_;
NSPersistentStoreCoordinator* persistentStoreCoordinator_;
}
@property (nonatomic, retain, readonly) NSURL* storeURL;
@property (nonatomic, retain, readonly) NSManagedObjectContext*
managedObjectContext;
@property (nonatomic, retain, readonly) NSManagedObjectModel*
managedObjectModel;
@property (nonatomic, retain, readonly) NSPersistentStoreCoordinator*
persistentStoreCoordinator;
@end
@implementation SomeDelegateOrControllerOrElse (CoreDataAdditions)
// property storeURL
- (NSURL*) storeURL {
// ...
return aURL; // return a URL where you want to have your persistent store
saved.
}
- (NSManagedObjectContext*) managedObjectContext {
if (managedObjectContext_ == nil) {
NSPersistentStoreCoordinator* coordinator = [self
persistentStoreCoordinator];
if (coordinator != nil) {
managedObjectContext_ = [[NSManagedObjectContext alloc] init];
[managedObjectContext_ setPersistentStoreCoordinator:coordinator];
}
}
return managedObjectContext_;
}
- (NSManagedObjectModel*) managedObjectModel {
if (managedObjectModel_ == nil) {
NSURL* modelURL = [[NSBundle mainBundle] URLForResource:@"MyModel"
withExtension:@"momd"];
managedObjectModel_ = [[NSManagedObjectModel alloc]
initWithContentsOfURL:modelURL];
}
return managedObjectModel_;
}
- (NSPersistentStoreCoordinator* )persistentStoreCoordinator {
if (persistentStoreCoordinator_ == nil) {
NSError* error = nil;
persistentStoreCoordinator_ = [[NSPersistentStoreCoordinator alloc]
initWithManagedObjectModel:[self managedObjectModel]];
if (![persistentStoreCoordinator_
addPersistentStoreWithType:NSSQLiteStoreType
configuration:nil
URL:self.storeURL
options:nil
error:&error])
{
// Replace this implementation with code to handle the error
appropriately.
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
}
return persistentStoreCoordinator_;
}
...
@end
As others already suggested, please read the corresponding documentation.
especially:
the "Core Data Programming Guide"
and
<http://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/CoreDataUtilityTutorial/CoreDataUtilityTutorial.pdf>
This sample shows the very basics, without any additional fuzz.
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