How to delete the NSManagedObject instance from Data Source? - iphone

Question

I am trying to override tableView:commitEditingStyle:editingStyleforRowAtIndexPath: and having trouble implementing the deletion of the actual instance of a NSManagedObject that is represented in that row.
Apple says it should be done with the following code(Shown Here):
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
if (editingStyle == UITableViewCellEditingStyleDelete) {
// Delete the managed object at the given index path.
NSManagedObject *eventToDelete = [eventsArray objectAtIndex:indexPath.row];
[managedObjectContext deleteObject:eventToDelete];
// Update the array and table view.
[eventsArray removeObjectAtIndex:indexPath.row];
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:YES];
// Commit the change.
NSError *error = nil;
if (![managedObjectContext save:&error]) {
// Handle the error.
}
}
}
When I mimick this sample code in my app, every line works except for one line. The one line is: [bowlerArray removeObjectAtIndex:indexPath.row];. I get the error "Receiver type 'NSArray' for instance message does not declare a method with selector 'removeObjectAtIndex'".
What should that one line of code be?
Note: My line NSManagedObject *eventToDelete = [bowlerArray objectAtIndex:indexPath.row]; works just fine.
Update: Posting my actual code:
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if (editingStyle == UITableViewCellEditingStyleDelete) {
// Delete the row from the data source
AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
NSManagedObjectContext *moc = [appDelegate managedObjectContext];
NSManagedObject *objectToDelete = [bowlerArray objectAtIndex:indexPath.row];
[moc deleteObject:objectToDelete];
[bowlerArray removeObjectAtIndex:indexPath.row];
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
}
else if (editingStyle == UITableViewCellEditingStyleInsert) {
// Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
}
}

Answer 1

NSArray is immutable, so you can't modify it.
removeObjectAtIndex is not part of the NSArray API, because it would modify it.
You need an NSMutableArray to be able to do that.
If I do this :
NSMutableArray *arMu = [NSMutableArray arrayWithObjects:#"0", #"1", #"2", #"3", #"4", nil];
[arMu removeObjectAtIndex:0];
self.bigLabel.text = [arMu objectAtIndex:0];
the bigLabel is showing 1 for the index 0.
You error message is suggesting that you still have a NSArray instead of an NSMutableArray for the variable eventsArray
You can make a NSMutableArray from a NSArray like this :
NSMutableArray *arMu = [[NSMutableArray alloc] initWithArray:someNSArray];