How to add indexTitles in a collection view? (iOS 10+)

Question

As the question, I'm trying to add an "index titles" in a collection view for a fast navigation of the contents of my UIColletionView.

I've read that, starting from iOS 10, method like indexTitles(for:) and collectionView(_:indexPathForIndexTitle:at:) can help me in that as in the UITableViews. But I'm not getting any result! Have you figured out how to use those methods? Thanks in advance for any help.

I posted a question on Apple Developer Forums https://forums.developer.apple.com/thread/95644 — nambatee, Jan 23 '18 at 19:53
@PatrickBodet I haven't worked on the project since then but I've found this: https://github.com/kreeger/BDKCollectionIndexView . I'll give it a try when I'll have time but maybe it works! — Alessandro Francucci, Feb 10 '18 at 11:16

score 7 · Accepted Answer · answered Feb 22 '18 at 14:52

If you look at UICollectionView.h, indexTitlesForCollectionView is only available in tvos:

/// Returns a list of index titles to display in the index view (e.g. ["A", "B", "C" ... "Z", "#"])
- (nullable NSArray<NSString *> *)indexTitlesForCollectionView:(UICollectionView *)collectionView API_AVAILABLE(tvos(10.2));

You might have read Apple's documentation, which states that indexTitle methods are available for iOS 10.3+ and tvOS 10.2+: https://developer.apple.com/documentation/uikit/uicollectionviewdatasource/2851455-indextitles

I tried implementing it on iOS and it just doesn't work, which leads me to believe that somehow they made a mistake in the documentation.

Leon · Answer 2 · 2020-12-28T15:21:44.280

I got the titles working on iPhones only by adding the following to my data source:

func indexTitles(for collectionView: UICollectionView) -> [String]? {
    guard !RunUtilities.isIpad else { return nil }
    return Array(Set(objects.map{ String($0.name.prefix(1)) })).sorted(by: { $0 < $1 })
}

func collectionView(_ collectionView: UICollectionView, indexPathForIndexTitle title: String, at index: Int) -> IndexPath {
    guard let index = objects.firstIndex(where: { $0.name.prefix(1) == title }) else {
        return IndexPath(item: 0, section: 0)
    }
    return IndexPath(item: index, section: 0)
}

EDIT: It looks like this is working from iOS 14 onwards. I installed the 13.4 runtime and the titles don't show.

How to add indexTitles in a collection view? (iOS 10+)

2 Answers2