Uninstall Xcode

sudo /Developer/Library/uninstall-devtools –mode=all

Core data Basics -Part 1

Welcome to the world of core data
________________________________________

step 1) import core data framework

step 2) create a coredata object -> Test.xcdatamodeld
create entity -> Class
Create Attributes-> Name , Descrioptin;

step3) in AppDelegate class add these

NSManagedObjectContext *managedObjectContext_;
NSManagedObjectModel *managedObjectModel_;
NSPersistentStoreCoordinator *persistentStoreCoordinator_;


@property (nonatomic, retain, readonly) NSManagedObjectContext *managedObjectContext;
@property (nonatomic, retain, readonly) NSManagedObjectModel *managedObjectModel;
@property (nonatomic, retain, readonly) NSPersistentStoreCoordinator *persistentStoreCoordinator;

- (NSURL *)applicationDocumentsDirectory;
- (void)saveContext;


###################################################

______________ in App delegate.m____________________________


#pragma mark -
#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_;
}


/**
Returns the managed object model for the application.
If the model doesn't already exist, it is created from the application's model.
*/
- (NSManagedObjectModel *)managedObjectModel {

if (managedObjectModel_ != nil) {
return managedObjectModel_;
}
NSString *modelPath = [[NSBundle mainBundle] pathForResource:@"Test" ofType:@"momd"];
NSURL *modelURL = [NSURL fileURLWithPath:modelPath];
managedObjectModel_ = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
return managedObjectModel_;
}


/**
Returns the persistent store coordinator for the application.
If the coordinator doesn't already exist, it is created and the application's store added to it.
*/
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {

if (persistentStoreCoordinator_ != nil) {
return persistentStoreCoordinator_;
}

NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"Test.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 -
#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];
}







#################################

_______________ in VeiwControll.h___

step5) create text fields to enter user values
UITextField* nameTextField;
UITextField* descriptionTextField;
UITextView* ingredientsTextView;
}
@property (nonatomic,retain) IBOutlet UITextField* nameTextField;
@property (nonatomic,retain) IBOutlet UITextField* descriptionTextField;
@property (nonatomic,retain) IBOutlet UITextView* ingredientsTextView;



##################

_______________in VC.m_____________


step6) to save the data in Sqlite


- (IBAction)save:(id)sender {

CoreData_rahul_saveDataAppDelegate* delegate = [[UIApplication sharedApplication] delegate];

NSManagedObjectContext* managedObjectContext = delegate.managedObjectContext;

NSManagedObject *nam;
nam=[NSEntityDescription insertNewObjectForEntityForName:@"Class" inManagedObjectContext:managedObjectContext];

[nam setValue:nameTextField.text forKey:@"Name"];
[nam setValue:descriptionTextField.text forKey:@"Desciption"];


NSError* error;
[managedObjectContext save:&error];

[self fetchRecords]; // to show data in console
}



step 7) to display data in console we use Fetch Request


- (void)fetchRecords {

CoreData_rahul_saveDataAppDelegate* delegate = [[UIApplication sharedApplication] delegate];

NSManagedObjectContext* managedObjectContext = delegate.managedObjectContext;

NSFetchRequest *request = [[NSFetchRequest alloc] init];

[request setEntity:[NSEntityDescription entityForName:@"Class" inManagedObjectContext:managedObjectContext]];

NSError *error = nil;
NSArray *events = [managedObjectContext executeFetchRequest:request error:&error];
NSAssert2(events != nil && error == nil, @"Error fetching events: %@\n%@", [error localizedDescription], [error userInfo]);
//You were leaking your request here
[request release], request = nil;
//The following line is redundant. You are leaking an array here
//NSMutableArray *namesArray = [[NSMutableArray alloc]init];
NSArray *namesArray = [events valueForKey:@"Name"];

NSLog(@"array us %@",namesArray);


}





Thanks

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App Shopper: iDraws (Lifestyle)

retain and Copy diff

In a general setting, retaining an object will increase its retain count by one. This will help keep the object in memory and prevent it from being blown away. What this means is that if you only hold a retained version of it, you share that copy with whomever passed it to you.

Copying an object, however you do it, should create another object with duplicate values. Think of this as a clone. You do NOT share the clone with whomever passed it to you.