Swift获取当前显示的索引UICollectionView

I'm making a music player for ios. I have a list of music and a detail view that you can swipe left and right to change the songs. The problem is I can't get the current displayed element to play the appropriate song, but the image displayed are good. I would like to know how can I get the current element in the Carousel View, because cellForItemAt doesn't work, when I swipe right it gives me the 2 next indexes.I'm making a music player for ios. I have a lis