How to edit the value of some attribute in entity? - ios

Question

How do I edit the value of some field in CoreData entity (SQLite) by tapping to Button?
For example, in my UITableViewCell I have button. I would like this button to change the value of some boolean field. By tapping first time I would like to write YES and second time - NO.
1.Join is a manually created join table Ingredients<->>Join<<->Recipes
2._ingredientInfo contain only 1 record
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"cellIngredient";
IngredientCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[IngredientCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
// Configure the cell...
Ingredients *ingredient = [ingredientsArray_ objectAtIndex:indexPath.row];
cell.nameLabel.text = ingredient.name;
//Указываем что-то типа DataSource
AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
NSManagedObjectContext *context = appDelegate.managedObjectContext;
if (context != nil) {
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"inRecipe == %# AND ingredient == %#", self.recipe, ingredient];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Join" inManagedObjectContext:context];
[request setEntity:entity];
[request setPredicate:predicate];
NSError *error = nil;
NSMutableArray *mutableFetchResult = [[context executeFetchRequest:request error:&error] mutableCopy];
if (mutableFetchResult == nil) {
NSLog(#"No fetched objects!!!");
abort();
}
_ingredientInfo = [mutableFetchResult objectAtIndex:0];
}
cell.countLabel.text = [NSString stringWithFormat:#"%#", _ingredientInfo.count];
if (_ingredientInfo.inCart == [NSNumber numberWithInt:0]) {
cell.toCartBtn.imageView.image = [UIImage imageNamed:#"runTo.png"];
}
else {
cell.toCartBtn.imageView.image = [UIImage imageNamed:#"inCart.png"];
}
cell.unitLabel.text = ingredient.units;
return cell;
}
and when I tap the button cell.toCartBtn
- (IBAction)toCart:(id)sender
{
if (_ingredientInfo.inCart == [NSNumber numberWithInt:0]) {
_ingredientInfo.inCart = [NSNumber numberWithInt:1];
}
else {
_ingredientInfo.inCart = [NSNumber numberWithInt:0];
}
NSError *error = nil;
AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
if ([appDelegate.managedObjectContext save:&error]) {
[self.ingredientsTableView reloadData];
}
else {
NSLog(#"Error updating");
}
}

Answer 1

First fetch your object to be modified
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"entityName" inManagedObjectContext:managedObjectContext];
[fetchRequest setEntity:entity];
[fetchRequest setPredicate:[NSPredicate predicateWithFormat:#"(id == %#)", eID]];
NSError *error;
NSArray *details = [managedObjectContext executeFetchRequest:fetchRequest error:&error];
entityName *objEntity= nil;
//error handling goes here
if([details count] > 0)
objEntity = (entityName *)[details objectAtIndex:0];
Now update that entity as you insert it
if(objEntity){
club.fieldName = #"YES";
NSError *error = nil;
if(![self.managedObjectContext save:&error])
NSLog(#"Error updating");
}