Redrawing UITableViewCell when entering/exiting edit mode

Question

I have a table view in which the cells are built differently depending on whether the table is editing or not. Specifically, the selection style is none when in edit mode and blue when not in edit mode.

When I transition from one to the other, I noticed that some of the cells are not updated. A quick bit of logging tells me that even though the cells' appearance changes quite drastically (accessory views are added/removed correctly for example) the table view does not refresh the selection style (nor for that matter the text).

What is going on here? Are only some attributes of the cell updated when setEditing is called? Presumably only those with a specific method allowing allocation of a separate view style (for example the EditingAccessoryType)? I guess I would benefit from a EditingSelectionStyle.

How should I resolve it? By customizing setEditing to change the selectionStyle for each cell? I'm not even sure how I would iterate through the table view to do this. reloadData isn't an option because of some animation that I am using.

Answer 1

I found that customizing setEditing: to iterate through the visible cells and setting the selectionStyle for each to work ok.

- (void)setEditing:(BOOL)editing animated:(BOOL)animated{   
    [super setEditing:editing animated:animated];

    for (UITableViewCell *cell in [self.tableView visibleCells]) {
            NSIndexPath *path = [self.tableView indexPathForCell:cell];
            cell.selectionStyle = (self.editing && (path.row > 1 || path.section == 0)) ? UITableViewCellSelectionStyleNone : UITableViewCellSelectionStyleBlue;
    }
}

Answer 2

If you look at the UITableViewDelegate documentation you will see a that there are five methods to customize the editing behavior. There is also the method

    - (BOOL)tableView:(UITableView *)tableView 
canEditRowAtIndexPath:(NSIndexPath *)indexPath

in the UITableViewDataSource documentation that will be called on each cell before you go into editing mode. The same is true for

- (UITableViewCellEditingStyle)tableView:(UITableView *)tableView 
           editingStyleForRowAtIndexPath:(NSIndexPath *)indexPath

that will get called for all cells that are editable. If you want to change the way the cells look you could do it in either of these. (Not implementing canEditRow.. assumes all rows are editable.)

---

Also note that there may be other ways to enter editing mode such as swiping on a cell, in which case

             - (void)tableView:(UITableView *)tableView 
willBeginEditingRowAtIndexPath:(NSIndexPath *)indexPath

will be called for the cell that you swiped on:

When entering this "swipe to delete" editing mode, the table view sends a tableView:willBeginEditingRowAtIndexPath: message to the delegate to allow it to adjust its user interface.

Answer 3

This works on Swift 2.3, just overwriting the setEditing method in your custom cell subclass:

class MyCell: UITableViewCell {

    override func setEditing(editing: Bool, animated: Bool) {
        super.setEditing(editing, animated: animated)
        //Place your code here...
    }

}