Draggin Inifite scroll of Collectionview

scroll.swift

func scrollFromDragging() {//need pageEnabled.
        guard let scrollView = self.collectionView else { return }
        
        var index = Int((scrollView.contentOffset.x) / (scrollView.frame.width))
        guard currentIndex != index, let banners = banners, rolling == false, isDragging == true else {
            return
        }
        
        var condition = currentIndex < 0 ? 0 : 3
        condition = index == 0 && currentIndex >= 0 ? 1 : condition
        condition = index >= banners.count + 1 ? 2 : condition
        
        currentIndex = index
        var offset = CGFloat.leastNormalMagnitude
        switch condition {
        case 0://최초 드래깅
            index = (fakeRowCount / 2)
            offset = index * scrollView.frame.width - 1
            //rollingIndex = 0
            Log.d("case == 0")
        case 1://0번 인덱스 이전으로 드래깅시
            index = (fakeRowCount / 2)
            offset = (index + 1) * scrollView.frame.width - 1
            Log.d("case == 1")
        case 2://마지막 드래깅시
            index = 0
            offset = scrollView.frame.width
            Log.d("case == 2")
        default:
            index -= 1
        }

        if offset > CGFloat.leastNormalMagnitude {
            scrollView.setContentOffset(CGPoint(x: offset, y: 0), animated: false)
        }
    }