编辑时在reloadData之后不会保留tableview选择指示

Question

I have a UITableView in a UIViewController . It's Selection modes are set to Single and Multiple Selection During Editing .

When I set the tableView's editing property to YES , if a process asynchronously runs reloadData , any of my current check marks that have been selected disappear. I implemented my tableView:cellForRowAtIndexPath: method such that it sets the selected property of the cell, based on what the selection was before the reloadData . I've verified those are being set correctly. But to no avail, they still don't show up selected. What do I need to change so that it gets that set correctly? It seems to retain the indented editing mode just fine.

Here's said method:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *CellIdentifier = @"ValveCell";
    ValveCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
    Valve *valve = self.sections[indexPath.section][indexPath.row];
    cell.subject = valve;
    cell.selected = [self.selections member: valve];
    return cell;
}

I use the didSelect and didDeselect methods to keep selections (an NSMutableSet ) up to date. Eg

- (void) tableView:(UITableView *)tableView didDeselectRowAtIndexPath:(NSIndexPath *)indexPath {
    NSMutableArray *section = self.sections[indexPath.section];
    [self.selections removeObject: section[indexPath.row]];
}

Clarification

Given the answers, I think I did not clarify which check marks I was referring to. I am referring to the blue check marks that show a selected state on the left side of the table when the table has had its editing set to YES as shown in this picture:

If a reloadData occurs, it will clear those blue check marks.

Update: My Current Solution

What I did to retain the visual selection status is to modify the KVO method that was firing the reloadData to include code to programmatically reselect the current selections:

...
[self.tableView reloadData];
if (self.tableView.editing) {
    [self.sections enumerateObjectsUsingBlock:^(id valves, NSUInteger section, BOOL *stop) {
         [(NSArray*)valves enumerateObjectsUsingBlock:^(id valve, NSUInteger row, BOOL *stop) {
             if ([self.selections member: valve]) {
                 NSIndexPath *indexPath = [NSIndexPath indexPathForRow: row inSection: section];
                 [self.tableView selectRowAtIndexPath: indexPath animated: NO scrollPosition: UITableViewScrollPositionNone];
             }
         }];
    }];
}
...

The selectRowAtIndexPath:animated:scrollPosition: method does the work.

So at this point, I guess my question is, do I really have to do this? Or I'm working too hard?

Answer 1

Setting the cell to "selected" in cellForRowAtIndexPath won't force a call to the UITableView delegate methods so if that's where you're setting your checkmarks, they won't automatically appear upon the table view's reload.

You can either add the checkmarks directly in cellForRowAtIndexPath , ex:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *CellIdentifier = @"ValveCell";
    ValveCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
    Valve *valve = self.sections[indexPath.section][indexPath.row];
    cell.subject = valve;
    cell.selected = [self.selections member: valve];

    if (cell.selected) {
        cell.accessoryType = UITableViewCellAccessoryCheckmark;
    } else {
        cell.accessoryType = UITableViewCellAccessoryNone;
    }

    return cell;
}

Or you can call selectRowAtIndexPath manually, ex:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *CellIdentifier = @"ValveCell";
    ValveCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
    Valve *valve = self.sections[indexPath.section][indexPath.row];
    cell.subject = valve;
    cell.selected = [self.selections member: valve];

    if (cell.selected) {
        [self tableView:tableView selectRowAtIndexPath:indexPath animated:NO scrollPosition:UITableViewScrollPositionNone]; 
    }

    return cell;
}