Implement twitter Profile like view with parallax

问题:

I want to implement the following sort of view where the view can be completely scrolled and houses 2 different scrollview (Main and the secondary) with infinite scrollable content. This represents the exact thing I want.

1. The red view is superview - should scroll vertically
2. The green view is of the height of the current view and is just static. That doesnt scroll
3. The blue view is the horizontal scrollview where for each label there is a yellow vertically scrolling infinity collection view
4. the labels scroll as in the given video. under each label there is the collection view I mentioned in point 3

The blue box is the scroll view and I want the scrolling to happen horizontally in a parallax way such as this.

I am able to implement the above parallax in the correct fashion but each title contains their own collectionview. When I implement this I am not able to have an infinite scroll. Below is the code for that :

func scrollViewDidScroll(_ scrollView: UIScrollView) {
    if scrollView == containerScrollView {
        for i in 0..<shotsData.count {
            let label = scrollView.viewWithTag(i + tagValueL) as! UILabel
            let view = scrollView.viewWithTag(i + tagValueV) as! ShotsMediaView
            let scrollContentOffset = scrollView.contentOffset.x + scrollView.frame.width
            let viewOffset = (view.center.x - scrollView.bounds.width/4) - scrollContentOffset
            label.center.x = scrollContentOffset - ((scrollView.bounds.width/4 - viewOffset)/2)
        }
    }
}

How can I exactly achieve the same behavior with an infinite scroll vertically? I want each of these titles to have collectionview that have the dynamic height each.

回答1:

I did a crude implementation of this.

func scrollViewDidScroll(_ scrollView: UIScrollView) {
    if scrollView == colorsCollectionView {
        let newContentOffSetX = scrollView.contentOffset.x
        let distance = contentOffSetX + newContentOffSetX
        // Scroll the text collection view proportinately
        let titleScrollDistance = (distance/colorsCollectionView.frame.width * 75.0)
        titlesCollectionView.contentOffset = CGPoint(x: titleScrollDistance, y: titlesCollectionView.contentOffset.y)
        contentOffSetX = newContentOffSetX
    }
}

contentOffSetX is a property of the class(ViewController) that I use to keep track of the scrolling distance of the bottom collection view. Initially that is set to 0. When the user scrolls the collection view at the bottom, the above delegate method is called. Then I use the contentOffSet to get the distance that was scrolled along the X-axis. I map that to the width of the title labels(hardcoded as 75.0) to calculate the distance that collection has to be scrolled. Hope this can be refined to serve your purpose, but I am sure that there are better methods out there :)