# init(from:to:changedObjects:) Creates a change details object that summarizes the differences between two fetch results. ``` convenience init(from fromResult: PHFetchResult, to toResult: PHFetchResult, changedObjects: [ObjectType]) ``` ## Parameters `fromResult` A fetch result to be treated as the “before” state in the resulting change details object. `toResult` A fetch result to be treated as the “after” state in the resulting change details object. `changedObjects` An collection of objects to manually note as changed between the two fetch results. ## Return Value A change details object. ## Discussion Typically, you use the [`PHChange`](/documentation/Photos/PHChange) class to retrieve [`PHFetchResultChangeDetails`](/documentation/Photos/PHFetchResultChangeDetails) objects describing any changes that have occurred since you performed a fetch, but you can also use this method to get a change details object that summarizes the difference between two arbitrary [`PHFetchResult`](/documentation/Photos/PHFetchResult) objects. In this case, Photos cannot automatically determine when the same objects are present in both fetch results but those objects’ content has changed, so the [`changedIndexes`](/documentation/Photos/PHFetchResultChangeDetails/changedIndexes) and [`changedObjects`](/documentation/Photos/PHFetchResultChangeDetails/changedObjects) properties are empty. However, you can use the `changedObjects` parameter to manually note objects as changed. For example, consider a view controller that maintains a base fetch result representing a list of albums, and a transient collection that filters the list according to the user’s search terms. For this workflow, you might use a method like the following: ```swift func filteredResult(for fetchResult: PHFetchResult) -> PHFetchResult { var filteredAlbums = [PHCollection]() fetchResult.enumerateObjects { collection, _, _ in if let title = collection.localizedTitle, let searchText = self.searchBar.text, title.hasPrefix(searchText) { filteredAlbums.append(collection) } } let filteredList = PHCollectionList.transientCollectionList(with: filteredAlbums, title: nil) return PHCollection.fetchCollections(in: filteredList, options: nil) } ``` Because transient collections are not stored in the photo library, Photos cannot provide change details for fetch results against a transient collection. The [`photoLibraryDidChange(_:)`](/documentation/Photos/PHPhotoLibraryChangeObserver/photoLibraryDidChange(_:)) method provides change details for the base fetch result, which you can use to request change details for the filtered fetch result: ```swift func photoLibraryDidChange(_ change: PHChange) { // This method may be called on a background queue; use the main queue to update the UI. DispatchQueue.main.async { guard let fetchResultChangeDetails = change.changeDetails(for: self.baseFetchResult) else { return } // Get the new base fetch result and filter it to get a new filtered result. self.baseFetchResult = fetchResultChangeDetails.fetchResultAfterChanges let previousFilteredResult = self.filteredFetchResult! self.filteredFetchResult = self.filteredResult(for: self.baseFetchResult) // Get the changed objects between the original and new base fetches // and use them for marking changes between the filtered fetches. let filteredChangeDetails = PHFetchResultChangeDetails( from: previousFilteredResult, to: self.filteredFetchResult, changedObjects: fetchResultChangeDetails.changedObjects) // Use the filtered change details to update the UI. self.updateView(for: filteredChangeDetails) } } ``` Because you provide the [`changedObjects`](/documentation/Photos/PHFetchResultChangeDetails/changedObjects) array from the original change details when calling the [`init(from:to:changedObjects:)`](/documentation/Photos/PHFetchResultChangeDetails/init(from:to:changedObjects:)) method, Photos can provide a summary of differences between the filtered fetch results that includes [`changedIndexes`](/documentation/Photos/PHFetchResultChangeDetails/changedIndexes) and [`changedObjects`](/documentation/Photos/PHFetchResultChangeDetails/changedObjects) information. You can then use this information for efficiently updating your app’s interface — for an example of how to do this, see [`PHPhotoLibraryChangeObserver`](/documentation/Photos/PHPhotoLibraryChangeObserver). --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)