UIMenuController在Cell内部无法显示的解决办法。

@implementation CollectionViewCell //继承自UICollectionViewCell

    UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPress:)];
        longPress.minimumPressDuration = 1;
        [self addGestureRecognizer:longPress];//添加长按手势

//实现长按方法
- (void)longPress:(UILongPressGestureRecognizer *)gesture
{
    switch (gesture.state) {
        case UIGestureRecognizerStateBegan:
        {
  　　　　　　//必须实现
            [self becomeFirstResponder];
            
            UIMenuController *menu = [UIMenuController sharedMenuController];
            
            UIMenuItem *item1 = [[UIMenuItem alloc] initWithTitle:@"保存" action:@selector(savePic)];
            
            menu.menuItems = [NSArray arrayWithObject:item1];

            [menu setTargetRect:self.scView.frame inView:self.scView.superview];
            
            [menu setMenuVisible:YES animated:YES];

        }
            break;
            
        default:
            break;
    }
}

//必须实现的方法，注意不是 - (void)becomeFirstResponse方法。
- (void)canBecomeFirstResponse
{
　　return YES;
}