两个iCarousel联动

像iPhone切换应用时一样的界面布局，上下两个iCarousel,拖动任一个，另一个跟着一块儿动。 https://github.com/nicklockwood/iCarousel/issues/231
ou can sync them perfectly. In the carouselDidScroll delegate
event of one carousel set the scrollOffset of the other carousel to match the first one (the scrollOffset is now readwrite and public)

iCarousel* carouselTop;
iCarousel* carouselBottom;

//当前正在拖动的carousel
iCarousel* _dragingCarousel;

- (void)carouselWillBeginDragging:(iCarousel *)carousel{
   _dragingCarousel = carousel;
}

- (void)carouselDidScroll:(iCarousel *)carousel{

    //不然会引起循环滚动。
   if(_dragingCarousel != carousel){
       return;
    }

    
   if(carousel ==
carouselTop ){

        carouselBottom.scrollOffset = carousel.scrollOffset;
    }elseif(carousel ==
carouselBottom ){

        carouselTop.scrollOffset = carousel.scrollOffset;
    }

    
}