moveRowAtIndexPath - Moving cells between sections

Question

In my UITableView I have this said relationship

Department -< Employees (array of names)

I have set up custom objects for each model.

Answer 1

Your problem is that you have manipulated the data model, but you haven't told the tableview about the changes you made.

Because you call beginUpdates/endUpdates the tableview is expecting some changes, so after endUpdates it calls numberOfRowsInSection - which returns the answer '3' - but it is expecting 2+0 (because you didn't tell it about the new row).

You have a couple of options:

1 - Use moveRowAtIndexPath:toIndexPath:

- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath
{
    if (fromIndexPath != toIndexPath ) {

        Department *department = [_objects objectAtIndex:fromIndexPath.section];
        Employee *employee = [department.employees objectAtIndex:fromIndexPath.row];

        [tableView beginUpdates];
        [department.employees removeObjectAtIndex:fromIndexPath.row];
        [department.employees insertObject:employee atIndex:toIndexPath.row];
        [tableview moveRowAtIndexPath:fromIndexPath toIndexPath:toIndexPath];
        [self.tableView endUpdates];
    }
}

2 - Use reload without the beginUpdate/endUpdate

- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath
{
    if (fromIndexPath != toIndexPath ) {

        Department *department = [_objects objectAtIndex:fromIndexPath.section];
        Employee *employee = [department.employees objectAtIndex:fromIndexPath.row];

        [department.employees removeObjectAtIndex:fromIndexPath.row];
        [department.employees insertObject:employee atIndex:toIndexPath.row];
        [tableView reloadData];
    }
}

Answer 2

Thanks to @Paulw11, the solution was that I did not account for the departmentFrom and departmentTo, as what I wanted was to Move Tom from Sales to Marketing;

Thus the fix I have is:

- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath
{
    if (fromIndexPath != toIndexPath ) {

        Department *departmentFrom = [_objects objectAtIndex:fromIndexPath.section];
        Department *departmentTo = [_objects objectAtIndex:toIndexPath.section];

        Employee *employee = [departmentFrom.employees objectAtIndex:fromIndexPath.row];

        [departmentFrom.employees removeObjectAtIndex:fromIndexPath.row];
        [departmentTo.employees insertObject:employee atIndex:toIndexPath.row];
        [tableView reloadData];
    }
}

Accepted Paulw11 answer.