在willDisplayCell中将UITableViewCell设置为YES：并且不能再取消选择单元格

Question

I want to pre-select some rows in a multiple selection UITableView.

I do this in tableView:willDisplayCell:forRowAtIndexPath: by simply setting [cell setSelected:YES animated:NO]; .

However, for some reason this disables deselection for these rows. The embedded controls still work, and so do detail disclosure buttons.

I have uploaded a sample project here: https://github.com/leberwurstsaft/TableViewIssue where you can check out the behavior (in Viewcontroller.m lines 49-51).

- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath {
    [cell setSelected:NO animated:NO]; //   -->   setSelected:YES and the cells can't be deselected anymore...
}

What seems to be the problem?

Answer 1

In addition to setting the cell as selected, you also need to inform the tableView that the cell is selected. Add a call to -tableView:selectRowAtIndexPath:animated:scrollPosition: to your willDisplayCell: method: and you will be able to deselect it as normal.

- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (/*should be selected */) {
        [cell setSelected:YES animated:NO]; 
        [tableView selectRowAtIndexPath:indexPath animated:NO scrollPosition:UITableViewScrollPositionNone];
    }
}

This is similar to @Ivan Loya's solution, but can be done in the same method you were already using. Be sure to use UITableViewScrollPositionNone to avoid odd scrolling behavior.

Answer 2

try this in view did appear, work for me

- (void)viewDidAppear:(BOOL)animated {
    NSIndexPath *indexPath=[NSIndexPath indexPathForRow:0 inSection:0];
    [_tableView selectRowAtIndexPath:indexPath animated:YES  scrollPosition:UITableViewScrollPositionBottom];
}

in your viewController.h add and link it to the table view

@property (weak, nonatomic) IBOutlet UITableView *tableView;

and comment the line in willDisplayCell Function

Answer 3

I think you should put your selection in - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath and toggle in there the selection.

Here is what I do in a similar situation where I want to toggle the checkmark on each row

(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{       
    [tableView deselectRowAtIndexPath:indexPath animated:NO];

    UITableViewCell *newCell = [tableView cellForRowAtIndexPath:indexPath];

    Person * person = [self.contactTable objectAtIndex:indexPath.row];

        if (newCell.accessoryType == UITableViewCellAccessoryNone)
        {
            newCell.accessoryType = UITableViewCellAccessoryCheckmark;
            person.isMatch = [NSNumber numberWithBool:YES];
            self.countChecked ++ ;


        }else
        {
            newCell.accessoryType = UITableViewCellAccessoryNone;
            person.isMatch = [NSNumber numberWithBool:NO];
            self.countChecked -- ;
        }
}

Answer 4

For those wondering in iOS 11 how to fix this:

Drew C, Got it right, But Im translating it to Swift:

func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {

    if cell.isSelected {
        cell.isSelected = true
        tableView.selectRow(at: indexPath, animated: false, scrollPosition: .none)
    }
}