saveLivePhotoToOutput:options:completionHandler:

Use this method when you have finished an editing session and need to provide rendered output in a PHContentEditingOutput object. Unlike when rendering output for a photo or video asset, you don’t need to provide rendered output using the renderedContentURL property of the editing output object. Instead, create a PHContentEditingOutput object using the initWithContentEditingInput: initializer, passing the same PHContentEditingInput object you used in the PHLivePhotoFrameProcessingBlock initializer to start this Live Photo editing context. Then pass that editing output object to this method, and Photos renders the Live Photo and provides it to the editing output.

After this method’s completion handler signals successful rendering, you use the content editing output to complete the edit. In an app using the Photos framework, create a PHAssetChangeRequest object inside a PHPhotoLibraryperformChanges block, and set its contentEditingOutput property to your editing output. In a photo editing extension running in the Photos app, your main view controller provides content editing output when requested by the finishContentEditingWithCompletionHandler: method.