iphone,是menucont.arrowDirection=uimenucontrollerarrowdown;不工作bug吗?

在点击我的标签栏后,我试图添加一个菜单控制器作为快速选择,但是当我使用时,我没有得到箭头。

menuCont.arrowDirection = UIMenuControllerArrowDown;

但是如果我用完了,不管是左边还是右边,都可以。

其他人能试试这个建议吗?

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

UITouch *touch = [[event allTouches] anyObject];

if ([touch tapCount] == 2) {
    [self becomeFirstResponder];
    UIMenuItem *menuItem = [[UIMenuItem alloc] initWithTitle:@"Blue" action:@selector(blueView)];
    UIMenuItem *menuItem2 = [[UIMenuItem alloc] initWithTitle:@"Green" action:@selector(greenView)];
    UIMenuItem *menuItem3 = [[UIMenuItem alloc] initWithTitle:@"Red" action:@selector(redView)];

    UIMenuController *menuCont = [UIMenuController sharedMenuController];
    [menuCont setTargetRect:CGRectMake(0,0,320,200) inView:self.view];
    menuCont.menuItems = [NSArray arrayWithObjects:menuItem, menuItem2, menuItem3, nil];
    menuCont.arrowDirection = UIMenuControllerArrowDown;
    [menuCont setMenuVisible:YES animated:YES];
}
}

- (void)blueView {
self.view.backgroundColor = [UIColor blueColor];
}
- (void)greenView {
self.view.backgroundColor = [UIColor greenColor];
}
- (void)redView {
self.view.backgroundColor = [UIColor redColor];
}

- (BOOL)canPerformAction:(SEL)action withSender:(id)sender {
BOOL answer = NO;

if (action == @selector(blueView)) 
    answer = YES;

if (action == @selector(greenView)) 
    answer = YES;

if (action == @selector(redView)) 
    answer = YES;

return answer;
}

- (BOOL)canBecomeFirstResponder {
return YES;
}

我想知道是不是它的老派,因为它不会自动完成时,输入一些菜单控制器代码?