Editing Asset Content

For each photo asset, Photos keeps a previous and a current version of its image data, as well as a PHAdjustmentData object that describes the last edit the user made to each asset’s content. Your app uses this information to support resumable editing.

When you begin editing an asset, Photos first asks whether your app can interpret the adjustment data from the most recent edit. If so, Photos provides the previous version of the asset as input for your editing session. After you read the adjustment data and reconstruct the edit it describes, your app might let the user alter or revert the last edit or make further changes. For example, adjustment data may describe filters applied to a photo. Your app reapplies those filters and allows the user to change filter parameters, add new filters, or remove filters.

If your app doesn't support an asset’s adjustment data, Photos provides the current version of the asset as input to your editing session. The current version contains the rendered output of all past edits, so your app can further edit the asset but cannot alter or revert most recent edit.

To support continuity of editing between different apps and extensions, Photos keeps the current and previous versions of each asset, along with a PHAdjustmentData object that describes the last edit. If your app supports the adjustment data from a previous edit, you can allow the user to revert or alter the edit.

Call the asset’s requestContentEditingInput(with:completionHandler:) method. The PHContentEditingInputRequestOptions object you provide for the options parameter controls whether your app can handle the asset’s adjustment data. Photos calls your completionHandler block, providing a PHContentEditingInput object you can use for retrieving the image or video data to be edited.

Apply your edits to the asset. To allow a user to continue working with your edits later, create a new PHAdjustmentData object describing the changes.

Initialize a PHContentEditingOutput object. For photo- or video-only assets, use the editing output’s properties to provide edited asset data. For Live Photo assets, create a PHLivePhotoEditingContext object to edit the Live Photo content.

Commit your edits to the photo library by posting a change block to the shared PHPhotoLibrary object. In the block, create a PHAssetChangeRequest object and set its contentEditingOutput property to the editing output that you created.

Each PHPhotoLibrary performChanges call prompts the user for permission to edit the contents of the photo library. To edit multiple assets in one batch, create multiple PHAssetChangeRequest objects within the same change block, each with its own corresponding PHContentEditingOutput object.