How to know that no row is selected in my UITableView? - ios

Question

I use a UITableView to display a list of items, and when a row is selected I show that item in a detail view next to it (using a split view controller).
As the selection in the table view changes I want my detail view to change as well, which is of course standard behavior and it works flawlessly... except when no row is selected anymore in the table view.
Users can for example delete a row from the table view, and during and also after that deletion there will be no selected row in the table view. Of course after a row is deleted I let my detail view controller know, but during the editing process in the table view, when no row is selected, my detail view controller does not know this.
I tried to use the UITableViewSelectionDidChangeNotification but that only gets sent when the user selects a different row, not when a deselection occurs.
How can I be notified of the fact that the table view switches from having a row selected to having no selection at all?
EDIT:
As a temporary solution, I tried renaming the Edit-button to "Reorder" and only allowing moving rows from A to B but without allowing the deletion controls, but this can not be done, there is no move control without enabling editing on a row. The thing is, I do get a pointer to a row that is up for moving, so I can keep that selected. I do not get this pointer for a row up for deletion, so no go for me. I always want to know what row a user works on, and keep that row selected at all times.
I may have to resort to ditching the standard editing behavior and adding my own buttons and methods for it. Or see what gestures can do for me to capture touches on any row...

Answer 1

There is a property indexPathForSelectedRow. I'm not sure what it would return when there is no selected row, but it may return nil or something like that, which you could use as a trigger to know if there are any rows selected. Something like
if (myTable.indexPathForSelectedRow == nil)
{
//do something here to account for no rows being selected
}
else
{
//do stuff here to set up your detail view
}
Let me know if this works for you.

Answer 2

How are you implementing the deletion of rows? Are you implementing the following data source method?
tableView:commitEditingStyle:forRowAtIndexPath:
You can have a property like
NSIndexPath *selectedIndexPath
and set it to nil when a row is being deleted.
Example:
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
//select another row in your table
[tableView selectRowAtIndexPath:*indexPathOfTheRowToBeSelected* animated:YES scrollPosition:UITableViewScrollPositionNone];
//then delete row from data source
}
The method above will be called when the user touches the delete button on the table he/she has selected to delete.

Answer 3

Okay I misread what you were asking at first, I'm pretty sure what you want is either – tableView:willDeselectRowAtIndexPath: or – tableView:didDeselectRowAtIndexPath:. These methods will be triggered automatically when the user deselects a row (either right before the row is deselected or right after, respectively). Implement one of these in your table view delegates code, and you'll know whenever a row gets deselected, and you can put your code to select the next row or whatever you want in one of these methods.

Answer 4

I struggled with this as well. Turns out that when the "Edit" button is hit, all rows are deselected at that point. You can override setEditing:animated: to detect when it is hit, but you must call [super setEditing:editing animated:animated] before you return.
See this link for where I found this:
How can i identify self.editButtonItem button's clicked event?