NSPopUpButton创建菜单与子菜单

      NSPopUpButton *popup = [[NSPopUpButton alloc] initWithFrame: 
      NSMakeRect(0, 0, 150, 22)];
      id item;
      NSMenuItem *menuItem;
      NSMenu *submenu;


      [popup setAutoenablesItems: NO];
    
      [popup addItemWithTitle: @"Marguerite"];
      [[popup itemWithTitle: @"Marguerite"] setEnabled: YES];
      [popup addItemWithTitle: @"Julie"];
      [[popup itemWithTitle: @"Julie"] setEnabled: YES];
      [popup addItemWithTitle: @"Liv"];
      [[popup itemWithTitle: @"Liv"] setEnabled: YES];
      [popup addItemWithTitle: @"Juliette"];
      [[popup itemWithTitle: @"Juliette"] setEnabled: YES];

      item = [popup itemWithTitle: @"Julies"];
      [popup selectItem: item];


      [toolbarItem setLabel: @"Just... popup"];
      [toolbarItem setView: popup];
    
      menuItem = [[NSMenuItem alloc] initWithTitle: @"More..." 
                                            action: NULL
                                     keyEquivalent: @""];
      submenu = [[NSMenu alloc] initWithTitle: @""];
      [submenu addItemWithTitle: @"Marguerite" 
                         action: @selector(reflectMenuSelection:) 
                  keyEquivalent: @""];
      [submenu addItemWithTitle: @"Julie" 
                         action: @selector(reflectMenuSelection:) 
                  keyEquivalent: @""];
      [submenu addItemWithTitle: @"Liv" 
                         action: @selector(reflectMenuSelection:) 
                  keyEquivalent: @""];
      [submenu addItemWithTitle: @"Juliette" 
                         action: @selector(reflectMenuSelection:) 
                  keyEquivalent: @""];
      [menuItem setSubmenu: AUTORELEASE(submenu)];
      [toolbarItem setMenuFormRepresentation: AUTORELEASE(menuItem)];