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fileprivate var smartAlbums = PHFetchResult<PHAssetCollection>()
fileprivate var userCreatedAlbums = PHFetchResult<PHAssetCollection>()
fileprivate func fetchPhotoAssets(){
/* fetches all smart albums like
favorites,
selfies,
screenshots,
livephotos,
panaramas etc in the user's photo library and stores it in a variable named "smartAlbums"
*/
smartAlbums = PHAssetCollection.fetchAssetCollections(with: .smartAlbum, subtype: .albumRegular, options: nil)
// fetches all of the user-created albums in the user's photo library and stores it in a variable named "userCreatedAlbums"
userCreatedAlbums = PHAssetCollection.fetchAssetCollections(with: .album, subtype: .albumRegular, options: nil)
}
If you’ve worked with the PhotoKit framework in the past to build a custom image picker, I’m sure you’ve had to write a similar code to the one above to fetch user’s smart albums and user-created albums.
The problem is users probably have a handful of empty albums in their photos library. To prevent us from cluttering the UI with empty PHAssetCollections there is a way for us to fetch only PHAssetCollections that contains at least one PHAsset (photo or video).
We accomplish that by applying predicate on a PHFetchOptions object. See below:
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fileprivate func fetchPhotoAssets(){
// fetches all of the non-empty user-created albums in the user's photo library and stores it in a variable named "userCreatedAlbums"
let userCreatedAlbumsOptions = PHFetchOptions()
userCreatedAlbumsOptions.predicate = NSPredicate(format: "estimatedAssetCount > 0")
userCreatedAlbums = PHAssetCollection.fetchAssetCollections(with: .album, subtype: .albumRegular, options: userCreatedAlbumsOptions)
}