UICollectionView - horizontal paging with one cell at a time

Question

I am trying to implement a carousel effect using collectionView. I implemented a UICollectionView and set it up to show the cells horizontally .

The only problem is how to allow only one cell to appear and center that cell on the screen.

Note. Paging enabled.

I found this code, tried it, but unfortunately did not work

Link to code: Create UICollectionView paging with Swift

 override func targetContentOffsetForProposedContentOffset(proposedContentOffset: CGPoint, withScrollingVelocity velocity: CGPoint) -> CGPoint { if let cv = self.collectionView { let cvBounds = cv.bounds let halfWidth = cvBounds.size.width * 0.5; let proposedContentOffsetCenterX = proposedContentOffset.x + halfWidth; if let attributesForVisibleCells = self.layoutAttributesForElementsInRect(cvBounds) { var candidateAttributes : UICollectionViewLayoutAttributes? for attributes in attributesForVisibleCells { // == Skip comparison with non-cell items (headers and footers) == // if attributes.representedElementCategory != UICollectionElementCategory.Cell { continue } if let candAttrs = candidateAttributes { let a = attributes.center.x - proposedContentOffsetCenterX let b = candAttrs.center.x - proposedContentOffsetCenterX if fabsf(Float(a)) < fabsf(Float(b)) { candidateAttributes = attributes; } } else { // == First time in the loop == // candidateAttributes = attributes; continue; } } return CGPoint(x : candidateAttributes!.center.x - halfWidth, y : proposedContentOffset.y); } } // Fallback return super.targetContentOffsetForProposedContentOffset(proposedContentOffset) } 

Answer 1

For the central cell above the code is correct, and implement these two methods:

 func scrollViewDidEndDecelerating(scrollView: UIScrollView) { let currentIndex:CGFloat = self.GridCollectionView.contentOffset.x / self.GridCollectionView.frame.size.width pageControl.currentPage = Int(currentIndex) } func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize { return CGSize(width: collectionView.frame.size.width, height: collectionView.frame.size.width+40) } 

Answer 2

If the element width is dynamic, you can try the code below

  - (CGPoint)targetContentOffsetForProposedContentOffset:(CGPoint)proposedContentOffset withScrollingVelocity:(CGPoint)velocity { CGFloat offsetAdjustment = MAXFLOAT; CGFloat proposedHorizontalCenter = proposedContentOffset.x + (CGRectGetWidth(self.collectionView.bounds) / 2.0); CGRect targetRect = CGRectMake(proposedContentOffset.x, proposedContentOffset.y, self.collectionView.bounds.size.width, self.collectionView.bounds.size.height); NSArray* array = [self layoutAttributesForElementsInRect:targetRect]; for (UICollectionViewLayoutAttributes* layoutAttributes in array) { CGFloat itemHorizontalCenter = layoutAttributes.center.x; if (ABS(itemHorizontalCenter - horizontalCenter) < ABS(offsetAdjustment)) { offsetAdjustment = itemHorizontalCenter - horizontalCenter; } } return CGPointMake(proposedContentOffset.x + offsetAdjustment, proposedContentOffset.y); }