Click detection on button inside NSCell

CustomNSCell.m

- (BOOL) trackMouse:(NSEvent *)event inRect:(NSRect)cellFrame ofView:(NSView *)controlView untilMouseUp:(BOOL)flag
{
    // Check if the button was hit.
    int hitType = [self hitTestForEvent:[NSApp currentEvent] inRect:cellFrame ofView:controlView];
    BOOL isButtonClicked = hitType == (NSCellHitContentArea | NSCellHitTrackableArea);
    if (!isButtonClicked) return YES;
    
    // Ignore events other than mouse down.
    if ([event type] != NSLeftMouseDown) return YES;
    
    // Grab all events until a mouse up event.
    while ([event type] != NSLeftMouseUp) {
        // Check if link arrow was hit.
        hitType = [self hitTestForEvent:[NSApp currentEvent] inRect:cellFrame ofView:controlView];
        isButtonClicked = hitType == (NSCellHitContentArea | NSCellHitTrackableArea);
        // Update the cell's display.
        [controlView setNeedsDisplayInRect:cellFrame];
        // Pass event if not hit.
        if (!isButtonClicked) {
            [NSApp sendEvent:event];
        }
        // Grab next event.
        event = [[controlView window] nextEventMatchingMask:(NSLeftMouseUpMask | NSLeftMouseDraggedMask | NSMouseEnteredMask | NSMouseExitedMask)];
    }
    
    // Perform click only if the button was hit.
    if (isButtonClicked) {
        [aButton performClick:self];
    }
    
    return YES;
}

- (IBAction)clickButton:(id)sender
{
    NSLog(@"here ... button was clicked");
}

gistfile1.m

[aButton setAction:@selector(clickButton:)]; // assign callback method after button clicked