UICollectionView with paging support

Question

I need to create a Grid view like iOS App App Store. I want to do this using swap UICollectionView. I also injected the code, but couldn't scroll it.

What I want to do is one image in the Center and on both sides (left and right), it should show part of the previous and next image. I set Frame for UICollectionView 320 * 320. The cell size is 290 * 320. (cell spacing is 10) 1

Below are two links that show my requirement. Thanks in advance.

(This is what I want) 2

Answer 1

UICollectionViewFlowLayout ?

[yourFlowLayout setScrollDirection:UICollectionViewScrollDirectionHorizontal];

:

[yourCollectionView setPagingEnabled:YES];

Answer 2

shtefane . cellWidth cellPadding.

- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView
                     withVelocity:(CGPoint)velocity
              targetContentOffset:(inout CGPoint *)targetContentOffset
{
    CGFloat cellWidth = self.cellWidth;
    CGFloat cellPadding = 9;

    NSInteger page = (scrollView.contentOffset.x - cellWidth / 2) / (cellWidth + cellPadding) + 1;

    if (velocity.x > 0) page++;
    if (velocity.x < 0) page--;
    page = MAX(page,0);

    CGFloat newOffset = page * (cellWidth + cellPadding);
    targetContentOffset->x = newOffset;
}

Answer 3

pagining collectionView, . . ScrollViewDelegate

- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset
 {
     CGFloat pageW = 300;
    int page = scrollView.contentOffset.x / pageW;

    CGFloat newOffset =(page + ((velocity.x > 0)? 1 : -1)) * (pageW - 20);
    CGPoint target = CGPointMake(newOffset, 0);
    targetContentOffset = ⌖
    NSLog(@"end Drag at %f /%i /%f",scrollView.contentOffset.x, page, velocity.x);

 }

, : , . UIScrollViewDelegate

Answer 4

Link to Rickster's answer, and I'm rewriting with Swift 4:

/* paging */
extension AlbumViewController {

    /* In case the user scrolls for a long swipe, the scroll view should animate to the nearest page when the scrollview decelerated. */
    override func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
        scrollToPage(scrollView, withVelocity: CGPoint(x:0, y:0))
    }

    override func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
        scrollToPage(scrollView, withVelocity: velocity)
    }

    func scrollToPage(_ scrollView: UIScrollView, withVelocity velocity: CGPoint) {
        let cellWidth: CGFloat = cellSize
        let cellPadding: CGFloat = 10

        var page: Int = Int((scrollView.contentOffset.x - cellWidth / 2) / (cellWidth + cellPadding) + 1)
        if velocity.x > 0 {
            page += 1
        }
        if velocity.x < 0 {
            page -= 1
        }
        page = max(page, 0)
        let newOffset: CGFloat = CGFloat(page) * (cellWidth + cellPadding)

        scrollView.setContentOffset(CGPoint(x:newOffset, y:0), animated: true)
    }
}

Answer 5

Here the working version of swift4 Rickster answers:

func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {

    let cellWidth = 174 as CGFloat
    let cellPadding = 10 as CGFloat

    var page = (scrollView.contentOffset.x - cellWidth / 2) / (cellWidth + cellPadding) + 1

    if (velocity.x > 0) { page += 1 }
    if (velocity.x < 0) { page -= 1 }

    page = max(page,0)

    targetContentOffset.pointee.x = page * (cellWidth + cellPadding)
}