NSTableView & NSOutlineView editing on tab key

Question

My app has an NSOutlineView and an NSTableView, and I'm having the same problem with both. With a row in either selected, pressing the tab key puts the first column into edit mode instead of making the next key view first responder. To get to the next key view, you need to tab through all of the columns.

Also, shift-tabbing into either view results in the last column going into edit mode, necessitating more shift-tabs to get into its previous key view.

In case it matters, I'm using the autocalculated key view loop, not my own, with my NSWindow set to autorecalculatesKeyViewLoop = YES. I would like tabbing between the columns once the user elects to edit a column, but I don't think it's standard behavior for the tab key to trigger edit mode.

Update

Thanks to the helpful responses below, I worked it out. Basically, I override -keyDown in my custom table view class, which handles tabbing and shift-tabbing out of the table view. It was tougher to solve shift-tabbing into the table view, however. I set a boolean property to YES in the custom table view's -acceptsFirstResponder if it's accepting control from another view.

The delegate's -tableView:shouldEditTableColumn:row checks for that when the current event is a shift-tab keyDown event. -tableView:shouldEditTableColumn:row is called and it's not a shift-tab event, it sets the table view's property back to NO so it can still be edited as usual.

I've pasted the full solution below.

/* CustomTableView.h */

@interface CustomTableView : NSTableView {}

@property (assign) BOOL justFocused;

@end

---

/* CustomTableView.m */

@implementation CustomTableView

@synthesize justFocused;

- (BOOL)acceptsFirstResponder {
    if ([[self window] firstResponder] != self) {
        justFocused = YES;
    }

    return YES;
}

- (void)keyDown:(NSEvent *)theEvent
{
    // Handle the Tab key
    if ([[theEvent characters] characterAtIndex:0] == NSTabCharacter) {
        if (([theEvent modifierFlags] & NSShiftKeyMask) != NSShiftKeyMask) {
            [[self window] selectKeyViewFollowingView:self];
        } else {
            [[self window] selectKeyViewPrecedingView:self];
        }
    }
    else {
        [super keyDown:theEvent];
    }
}

@end

---

/* TableViewDelegate.m */

. . .

- (BOOL)tableView:(NSTableView *)tableView shouldEditTableColumn:(NSTableColumn *)tableColumn
              row:(NSInteger)row
{
    NSEvent *event = [NSApp currentEvent];
    BOOL shiftTabbedIn = ([event type] == NSKeyDown
                          && [[event characters] characterAtIndex:0] == NSBackTabCharacter);

    if (shiftTabbedIn && ((CustomTableView *)tableView).justFocused == YES) {
        return NO;
    } else {
        ((CustomTableView *)tableView).justFocused = NO;
    }

    return YES;
}

. . .

Answer 1

This is the default behavior. If there's no row selected, the table view as a whole has focus, and the Tab key switches to the next key view. If there is a row selected, the table view begins editing or moves to the next cell if already editing.

From AppKit Release Notes:

Tables now support inter-cell navigation as follows:

• Tabbing forward to a table focuses the entire table.
• Hitting Space will attempt to 'performClick:' on a NSButtonCell in the selected row, if there is only one instance in that row.
• Tabbing again focuses the first "focusable" (1) cell, if there is one.
• If the newly focused cell can be edited, editing will begin.
• Hitting Space calls 'performClick:' on the cell and sets the datasource value afterwards, if changed. (2)
• If a text cell is editing, hitting Enter will commit editing and focus will be returned to the tableview, and Tab/Shift-tab will commit the editing and then perform the new tab-loop behavior.
• Tabbing will only tab through a single row
• Once the last cell in a row is reached, tab will take the focus to the next focusable control.
• Back tabbing into a table will select the last focusable cell.

If you want to change this behavior, the delegate method tableView:shouldEditTableColumn:row: may be helpful. You may also have to subclass NSTableView if you really want to affect only the behavior of the Tab key.

Answer 2

The solution using keyDown didn't work for me. Perhaps because it is for cell-based table view.

My solution for a view-based table view, in Swift, looks like this:

extension MyTableView: NSTextFieldDelegate {
    func controlTextDidEndEditing(_ obj: Notification) {
        guard
            let view = obj.object as? NSView,
            let textMovementInt = obj.userInfo?["NSTextMovement"] as? Int,
            let textMovement = NSTextMovement(rawValue: textMovementInt) else { return }

        let columnIndex = column(for: view)
        let rowIndex = row(for: view)

        let newRowIndex: Int
        switch textMovement {
        case .tab:
            newRowIndex = rowIndex + 1
            if newRowIndex >= numberOfRows { return }
        case .backtab:
            newRowIndex = rowIndex - 1
            if newRowIndex < 0 { return }
        default: return
        }

        DispatchQueue.main.async {
            self.editColumn(columnIndex, row: newRowIndex, with: nil, select: true)
        }
    }
}

You also need to set the cell.textField.delegate so that the implementation works.

My blog post on this tricky workaround: https://samwize.com/2018/11/13/how-to-tab-to-next-row-in-nstableview-view-based-solution/