如何在UITextfield中禁用UIMenuController的复制和定义UIMenuItems

我正在实施自定义UIMenuController并试图找出答案.我怎样才能合法地禁用"复制"和"定义"的UIMenuItems UIMenuController的UITextfield？Textfield不可编辑.我尝试使用以下命令禁用"复制":

-(BOOL)canPerformAction:(SEL)action withSender:(id)sender 
{
   if (action == @selector(copy:))
    {
        return NO;
    }

    return [super canPerformAction:action withSender:sender];
}


- (IBAction)tapTextViewGesture:(id)sender {

  UIMenuItem *myItem1 = [[UIMenuItem alloc] initWithTitle:@"myItem1" action:@selector(myItem1Pressed:)];
  UIMenuItem *myItem2 = [[UIMenuItem alloc] initWithTitle:@"myItem2" action:@selector(myItem2Pressed:)];
  UIMenuItem *myItem3 = [[UIMenuItem alloc] initWithTitle:@"myItem3" action:@selector(myItem3Pressed:)];

    // Access the application's shared menu
    UIMenuController *menu = [UIMenuController sharedMenuController];

    [menu setMenuItems:[NSArray arrayWithObjects:myItem1,myItem2,myItem3, nil]];

    CGRect menuRect = CGRectMake(20, 50, 200, 0);


    // Show the menu from the cursor's position
    [menu setTargetRect:menuRect inView:self.view];


    [menu setMenuVisible:YES animated:YES];
}

但菜单仍然显示"复制"和"定义" UIMenuItems.如何禁用它们,只留下我的物品？

最后通过子类化UITextView(为它创建自定义类)解决了它,并刚刚添加

- (BOOL)canPerformAction:(SEL)action withSender:(id)sender
{

    if (action == @selector(copy:))
    {
        return NO;
    }

    return NO;
}

在我的自定义TextView子类的.m文件中.

之后,"复制"不再出现,有或没有[menu update];