UICollectionViewCell will be displayed/ was displayed?

Question

pretty simple question.

Is there a notification or delegate-type method to tell when a UICollectionViewCell object is displayed?

Solution 1

For iOS 8 and higher you can use willDisplayCell of UICollectionViewDelegate

- (void)collectionView:(UICollectionView *)collectionView willDisplayCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath

Solution 2

Will:

-[<UICollectionViewDataSource> collectionView:cellForItemAtIndexPath:]

Did:

-[<UICollectionViewDelegate> collectionView:didEndDisplayingCell:forItemAtIndexPath:]

Comments

[W Dyson]

Being as iOS 8 is the current release, I'll mark this as correct. Thanks!

[Chris Prince]

@Dave DeLong: didEndDisplayingCell refers to the cell being removed from the collection view. From the Apple docs "Tells the delegate that the specified cell was removed from the collection view."

[Andrew Rozdolsky]

@titaniumdecoy: Actually collectionView:cellForItemAtIndexPath: will be called even if some cells were recycled. It's up to you to decide if you want to reuse recycled cell or create a new one inside this method.

[Rauli Rikama]

This doesn't actually tell if it's displayed on screen or not. Cell might be added off screen also. From the documentation: The collection view calls this method before adding a cell to its content. Use this method to detect cell additions, as opposed to monitoring the cell itself to see when it appears.

[zumzum]

this works for me. It gets called every time the cell comes back in view as I scroll it off and in the view... running iOS 13

[Zaporozhchenko Oleksandr]

it is called before cell will be displayed, not after it displayed.