objective-c – 仅对“源列表”中的某些项的上下文菜单

- (NSMenu *)menuForEvent:(NSEvent *)event;
{
    //The event has the mouse location in window space; convert it to our (the outline view's) space so we can find which row the user clicked on.
    NSPoint point = [self convertPoint:[event locationInWindow] fromView:nil];
    NSInteger row = [self rowAtPoint:point];

    //If the user did not click on a row,or is not exactly one level down from the top level of hierarchy,return nil—that is,no menu.
    if ( row == -1 || [self levelForRow:row] != 1 )
        return nil;

    //Create and populate a menu.
    NSMenu *menu = [[NSMenu alloc] init];
    NSMenuItem *delete = [menu addItemWithTitle:NSLocalizedString( @"Delete",@"" ) action:@selector(delete:) keyEquivalent:@""];

    [self selectRowIndexes:[NSIndexSet indexSetWithIndex:row] byExtendingSelection:NO];

    //Set the Delete menu item's represented object to the clicked-on item. If the user chooses this item,we'll retrieve its represented object so we know what to delete.
    [delete setRepresentedObject:[self itemAtRow:row]];

    return menu;
}

这假设我们正在使用ARC进行编译,因此您无需自动释放正在创建的菜单对象.