UITableView removing and adding rows - objective-c

Question

I have an NSMutableArray containing sequential numbers 1,2...,n and have a UITableView that displays cells vertically ascending and in order. How would I go about deleting a row, m between 1 and n, both visually and in the data, as well as in the NSMutableArray, and then decrement by 1 the value of all cells that followed the deleted cell in the data and visually such that the firstResponder does not resign control like a reloadData method call would?
#interface TableController : UIViewController
#property (nonatomic, retain) NSMutableArray *data;
#end
#implementation TableController
#synthesize data;
- (id)init
{
if(self = [super init]) {
data = [NSArray arrayWithObjects:#"1",#"2",#"3",#"4",#"5",nil];
}
return self;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [data count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [UITableViewCell new];
[cell.textLabel setText:[data objectAtRow:indexPath.row]];
return cell;
}
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
return 20;
}
#end
How would I remove row 3 and then make rows four and five then become 3 and 4 respectively?

Answer 1

Just edit your view model and then reload the table.
[data removeObjectAtIndex:2];
[tableView reloadData];
Another option is the UITableView method deleteRowsAtIndexPaths:withRowAnimation:. This approach is UI only, you must also update your view model in case the cells ever get reloaded at a later time. The advantage of this approach is that only the cells you specify get changed. Existing cells are not reloaded.
If the cell you are deleting is your first responder then you could handle this case by telling the next cell to become first responder.

Answer 2

For user driven deletion, your [tableview dataSource] should implement the method tableView:commitEditingStyle:forRowAtIndexPath:.
Here's an implementation from my code…
-(void) tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if(editingStyle == UITableViewCellEditingStyleDelete)
{
[[STLocationsModel sharedModel] deleteLocationAtIndex: [indexPath row]];
[tableView deleteRowsAtIndexPaths: #[indexPath] withRowAnimation: UITableViewRowAnimationLeft];
}
}
To allow editing, you'll also want…
-(BOOL) tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
{
return YES;
}
To get the table in to editing mode to allow deletions, you need to put it in to editing mode. You could place this in your viewDidLoad, or you might toggle it with a button:
[[self tableView] setEditing:YES animated:NO];
And if you also want to be able to make selections while the table is edited (again, this could go in your viewDidLoad…
[[self tableView] setAllowsSelectionDuringEditing: YES];