Detecting Vertical NSScroller hitting bottom in NSTableView

Question

Let's Say i loaded 100 rows in a table in awakeFromNib: , Now i want to call a method when the vertical scroller hits the bottom. Could anyone let me know how to handle the event of NSScroller hitting the bottom and calling a method when this happens.

Answer 1

// In awakeFromNib:
self.scrollView = [self.tableView enclosingScrollView];

// Register delegate to the scrollView content View:
// This will send notification whenever scrollView content view visible frame changes.
[NSNotificationCenter.defaultCenter addObserver:self selector:@selector(scrollViewDidScroll:) name:NSViewBoundsDidChangeNotification object:self.scrollView.contentView];

// This Method is called when content view frame changed
- (void)scrollViewDidScroll:(NSNotification *)notification {
    NSScrollView *scrollView = self.scrollView;
    // Test if bottom of content view is reached.
    CGFloat currentPosition = CGRectGetMaxY([scrollView visibleRect]);
    CGFloat contentHeight = [self.tableView bounds].size.height - 5;

    if (currentPosition > contentHeight - 2.0) {
        // YOUR ACTION
    }
}
// Remove observer
- (void)dealloc {
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

Answer 2

You can detect a scrollview at bottom by checking if tableView.enclosingScrollView.verticalScroller?.floatValue == 1 since the floatValue of vertical scroller varies between 0 and 1.