Change selection color on view-based NSTableView

Since you’re using the view based NSTableView, you can subclass NSTableRowView, feed it to the table delegate method - (NSTableRowView *)tableView:(NSTableView *)tableView rowViewForRow:(NSInteger)row;, then customize your selection in the row view class.

Here’s an example:

- (void)drawSelectionInRect:(NSRect)dirtyRect {
    if (self.selectionHighlightStyle != NSTableViewSelectionHighlightStyleNone) {
        NSRect selectionRect = NSInsetRect(self.bounds, 2.5, 2.5);
        [[NSColor colorWithCalibratedWhite:.65 alpha:1.0] setStroke];
        [[NSColor colorWithCalibratedWhite:.82 alpha:1.0] setFill];
        NSBezierPath *selectionPath = [NSBezierPath bezierPathWithRoundedRect:selectionRect xRadius:6 yRadius:6];
        [selectionPath fill];
        [selectionPath stroke];
    }
}