Deleting core data single entry through table iPhone - iphone

Question

Using core data to populate my table view. The thing I am not getting is that how can I delete a single entry from the core data.
Here is the code I am using:
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
if (tableView == favouritesTable) {
cellValue = [licensePlateArray objectAtIndex:indexPath.row];
} else { // handle search results table view
cellValue = [filteredListItems objectAtIndex:indexPath.row];
}
static NSString *CellIdentifier = #"vlCell";
VehicleListCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
NSLog(#"Cell Created");
NSArray *nibObjects = [[NSBundle mainBundle] loadNibNamed:#"VehicleListCell" owner:nil options:nil];
for (id currentObject in nibObjects) {
if ([currentObject isKindOfClass:[VehicleListCell class]]) {
cell = (VehicleListCell *)currentObject;
}
}
UILongPressGestureRecognizer *pressRecongnizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(tableCellPressed:)];
pressRecongnizer.minimumPressDuration = 0.5f;
[cell addGestureRecognizer:pressRecongnizer];
[pressRecongnizer release];
}
cell.textLabel.font = [UIFont systemFontOfSize:10];
Favouritesdata *favdata = [licensePlateArray objectAtIndex:indexPath.row];
[[cell ignition] setImage:[UIImage imageNamed:#"ignition.png"]];
[[cell direction] setImage:[UIImage imageNamed:#"south.png"]];
cell.licPlate.text = [favdata licenseplate];
NSLog(#"cellvalue for cellforRow: %#", cell.licPlate.text);
return cell;}
In the method of UILongPressGestureRecognizer:
- (void)tableCellPressed:(UILongPressGestureRecognizer *)recognizer{
if (recognizer.state != UIGestureRecognizerStateBegan) {
return;
}
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil message:nil delegate:self cancelButtonTitle:#"Cancel" otherButtonTitles: nil] ;
[alert addButtonWithTitle:#"Remove from Favourites"];
[alert addButtonWithTitle:#"Take to Map"];
[alert show];}
In alert view method:
-(void)alertView:(UIAlertView *)alert clickedButtonAtIndex:(NSInteger)buttonIndex {
NSString *title = [alert buttonTitleAtIndex:buttonIndex];
NSManagedObjectContext *contextFav = [app managedObjectContext];
Favouritesdata * favourites = [NSEntityDescription insertNewObjectForEntityForName:#"Favouritesdata" inManagedObjectContext:contextFav];
if([title isEqualToString:#"Remove from Favourites"])
{
NSLog(#"cellValueForLongPress: %#", cellValueForLongPress);
if (cellValueForLongPress <= 0) {
NSLog(#"No data to delete");
}
else {
favourites.licenseplate = cellValueForLongPress;
}
[alert dismissWithClickedButtonIndex:0 animated:YES];
}
else if([title isEqualToString:#"Take to Map"])
{
NSLog(#"Go to MapView");
}
NSError *error;
if (![context save:&error]) {
NSLog(#"Error Occured");
}}

Answer 1

If you want to delete managed object from CoreData storage then you should have:
Reference to NSManagedObjectContext from where you will remove object : context
Reference to NSManagedObject that you want to delete: object
Then it will be very simple to remove object:
[context deleteObject:object];
You should know
index of the row to remove, for example, i.
retrieve it from your array: NSObject *object = [licensePlateArray objectAtIndex:i];
remove it from db : [context deleteObject:object];
remove it from array: [licensePlateArray removeObject:object];

Answer 2

You have to identify your NSManagedObject and then call deleteObject on your managedObjectContext. Then this object will be removed from your core data.
But you have to provide a mechanism to "somehow" get the object behind a specific tableview row.