UICollectionView current visible cell index

Question

I am using UICollectionView first time in my iPad application  I have set UICollectionView such that its size and cell size is same  means only once cell is displayed at a time  Problem  Now when user scroll UICollectionView I need to know which cell is visible I have to update other UI elements on change  I didn t find any delegate method for this  How can I achieve this  Code   self mainImageCollection setTag MAIN IMAGE COLLECTION VIEW    self mainImageCollection registerClass  InspirationMainImageCollectionCell class  forCellWithReuseIdentifier   quot cellIdentifier quot     self mainImageFlowLayout setScrollDirection UICollectionViewScrollDirectionHorizontal    self mainImageFlowLayout setMinimumInteritemSpacing 0 0f    self mainImageFlowLayout setMinimumLineSpacing 0 0f   self mainImageFlowLayout minimumLineSpacing   0   self mainImageCollection setPagingEnabled YES    self mainImageCollection setShowsHorizontalScrollIndicator NO    self mainImageCollection setCollectionViewLayout self mainImageFlowLayout    What I have tried  As UICollectionView conforms to UIScrollView  I got when user scroll ends with UIScrollViewDelegate method - void scrollViewDidEndDecelerating  UIScrollView   scrollView  But inside above function how can I get current visible cell index of UICollectionView

User · Answer

Also check this snippet  let isCellVisible   collectionView visibleCells map   collectionView indexPath for   0    contains inspectingIndexPath

User · Answer

indexPathsForVisibleItems might work for most situations  but sometimes it returns an array with more than one index path and it can be tricky figuring out the one you want  In those situations  you can do something like this   CGRect visibleRect    CGRect   origin   self collectionView contentOffset   size   self collectionView bounds size   CGPoint visiblePoint   CGPointMake CGRectGetMidX visibleRect   CGRectGetMidY visibleRect    NSIndexPath  visibleIndexPath    self collectionView indexPathForItemAtPoint visiblePoint     This works especially well when each item in your collection view takes up the whole screen     Swift version     let visibleRect   CGRect origin  collectionView contentOffset  size  collectionView bounds size  let visiblePoint   CGPoint x  visibleRect midX  y  visibleRect midY  let visibleIndexPath   collectionView indexPathForItem at  visiblePoint

User · Answer

The method  collectionView visibleCells  give you all visibleCells array you want  Use it when you want to get  -  void scrollViewDidEndDecelerating  UIScrollView   scrollView      for  UICollectionViewCell  cell in  self mainImageCollection visibleCells             NSIndexPath  indexPath    self mainImageCollection indexPathForCell cell           NSLog       indexPath             Update to Swift 5   func scrollViewDidEndDecelerating   scrollView  UIScrollView        for cell in yourCollectionView visibleCells           let indexPath   yourCollectionView indexPath for  cell          print indexPath

User · Answer

In this thread  There are so many solutions that work fine if cell takes full screen but they use collection view bounds and midpoints of Visible rect However there is a simple solution to this problem      DispatchQueue main async           let visibleCell   self collImages visibleCells first         print self collImages indexPath for  visibleCell           by this  you can get indexPath of the visible cell  I have added DispatchQueue because when you swipe faster and if for a brief moment the next cell is shown then without dispactchQueue you ll get indexPath of briefly shown cell not the cell that is being displayed on the screen

User · Answer

UICollectionView current visible cell index  Swift 3  4 and 5  var visibleCurrentCellIndexPath  IndexPath        for cell in self collectionView visibleCells           let indexPath   self collectionView indexPath for  cell          return indexPath                      return nil    As an Extension  extension UICollectionView     var visibleCurrentCellIndexPath  IndexPath        for cell in self visibleCells         let indexPath   self indexPath for  cell        return indexPath                return nil        Usage  if let indexPath   collectionView visibleCurrentCellIndexPath           do something

User · Answer

You can use scrollViewDidEndDecelerating  for this     property  strong  nonatomic  IBOutlet UICollectionView  collectionView      -  void scrollViewDidEndDecelerating  UIScrollView   scrollView           for  UICollectionViewCell  cell in  self collectionView visibleCells                 NSIndexPath  indexPath    self collectionView indexPathForCell cell               NSUInteger lastIndex    indexPath indexAtPosition  indexPath length  - 1               NSLog   visible cell value  d  lastIndex

User · Answer

Swift 3 0  Simplest solution which will give you indexPath for visible cells    yourCollectionView indexPathsForVisibleItems    will return the array of indexpath   Just take the first object from array like this   yourCollectionView indexPathsForVisibleItems first   I guess it should work fine with Objective - C as well

User · Answer

This is old question but in my case     -  void  scrollViewWillBeginDragging  UIScrollView   scrollView         m offsetIdx    m cv indexPathForCell m cv visibleCells firstObject  row     -  void  scrollViewDidEndDecelerating  UIScrollView   scrollView        m offsetIdx    m cv indexPathForCell m cv visibleCells lastObject  row

User · Answer

Just want to add for others   for some reason  I didnt not get the cell that was visible to the user when I was scrolling to previous cell in collectionView with pagingEnabled   So I insert the code inside dispatch async to give it some  air  and this works for me   - void scrollViewDidEndDecelerating  UIScrollView   scrollView       dispatch async dispatch get main queue                   UICollectionViewCell   visibleCell    self collectionView visibleCells  objectAtIndex 0                  visibleCell doSomthing

User · Answer

Swift 5   func scrollViewDidEndDecelerating   scrollView  UIScrollView        var visibleRect   CGRect        visibleRect origin   collectionView contentOffset     visibleRect size   collectionView bounds size      let visiblePoint   CGPoint x  visibleRect midX  y  visibleRect midY       guard let indexPath   collectionView indexPathForItem at  visiblePoint  else   return         print indexPath      Working Answers Combined In Swift 2 2     func scrollViewDidEndDecelerating scrollView  UIScrollView             var visibleRect   CGRect            visibleRect origin   self collectionView contentOffset         visibleRect size   self collectionView bounds size          let visiblePoint   CGPointMake CGRectGetMidX visibleRect   CGRectGetMidY visibleRect            let visibleIndexPath  NSIndexPath   self collectionView indexPathForItemAtPoint visiblePoint           guard let indexPath   visibleIndexPath else   return            print indexPath

User · Answer

Swift 3  amp  Swift 4   func scrollViewDidEndDecelerating   scrollView  UIScrollView       var visibleRect   CGRect       visibleRect origin   collectionView contentOffset    visibleRect size   collectionView bounds size     let visiblePoint   CGPoint x  visibleRect midX  y  visibleRect midY      guard let indexPath   collectionView indexPathForItem at  visiblePoint  else   return        print indexPath 1       If you want to show actual number than you can add  1

User · Answer

It will probably be best to use UICollectionViewDelegate methods   Swift 3      Called before the cell is displayed     func collectionView   collectionView  UICollectionView  willDisplay cell  UICollectionViewCell  forItemAt indexPath  IndexPath        print indexPath row        Called when the cell is displayed func collectionView   collectionView  UICollectionView  didEndDisplaying cell  UICollectionViewCell  forItemAt indexPath  IndexPath        print indexPath row

User · Answer

For completeness sake  this is the method that ended up working for me  It was a combination of  Anthony  amp   iAn s methods   -  void scrollViewDidEndDecelerating  UIScrollView   scrollView         CGRect visibleRect    CGRect   origin   self collectionView contentOffset   size   self collectionView bounds size         CGPoint visiblePoint   CGPointMake CGRectGetMidX visibleRect   CGRectGetMidY visibleRect          NSIndexPath  visibleIndexPath    self collectionView indexPathForItemAtPoint visiblePoint         NSLog       visibleIndexPath

User · Answer

For Swift 3 0   func scrollViewDidScroll   scrollView  UIScrollView        let visibleRect   CGRect origin  colView contentOffset  size  colView bounds size      let visiblePoint   CGPoint x  visibleRect midX  y  visibleRect midY      let indexPath   colView indexPathForItem at  visiblePoint

User · Answer

converting  Anthony s answer to Swift 3 0 worked perfectly for me   func scrollViewDidScroll   scrollView  UIScrollView         var visibleRect   CGRect       visibleRect origin   yourCollectionView contentOffset     visibleRect size   yourCollectionView bounds size     let visiblePoint   CGPoint x  CGFloat visibleRect midX   y  CGFloat visibleRect midY       let visibleIndexPath  IndexPath    yourCollectionView indexPathForItem at  visiblePoint      print  Visible cell s index is     visibleIndexPath  row

User · Answer

try this  it works   in the example below i have 3 cells for example         func scrollViewDidEndDecelerating scrollView  UIScrollView        let visibleRect   CGRect origin  self collectionView contentOffset  size  self collectionView bounds size      let visiblePoint   CGPointMake CGRectGetMidX visibleRect   CGRectGetMidY visibleRect       let visibleIndexPath   self collectionView indexPathForItemAtPoint visiblePoint      if let v   visibleIndexPath           switch v item           case 0  setImageDescription               break         case 1  setImageConditions               break         case 2  setImageResults               break         default  break

[ios] UICollectionView current visible cell index

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