Is Photo Library access mandatory for 24MP Deferred Photo Capture?

Hello everyone,

I'm working on a feature where I need to capture the highest possible quality photo (e.g., 24MP on supported devices) and upload it to our server. I don't need the photos to appear in user's main Photos app so I thought I could store the photos in app's private directory using FileManager until they are uploaded. This wouldn't require requesting Photo Library permission, maximizing user privacy.

1. The documentation on AVCapturePhotoOutput states that "the 24MP setting (5712, 4284) is only serviced as 24MP when opted-in to autoDeferredPhotoDeliveryEnabled"

     /**
     @property maxPhotoDimensions
     @abstract
        Indicates the maximum resolution of the requested photo.
     
     @discussion
        Set this property to enable requesting of images up to as large as the specified dimensions. Images returned by AVCapturePhotoOutput may be smaller than these dimensions but will never be larger. Once set, images can be requested with any valid maximum photo dimensions by setting AVCapturePhotoSettings.maxPhotoDimensions on a per photo basis. The dimensions set must match one of the dimensions returned by AVCaptureDeviceFormat.supportedMaxPhotoDimensions for the current active format. Changing this property may trigger a lengthy reconfiguration of the capture render pipeline so it is recommended that this is set before calling -[AVCaptureSession startRunning].
        Note: When supported, the 24MP setting (5712, 4284) is only serviced as 24MP when opted-in to autoDeferredPhotoDeliveryEnabled.
     */
    @available(iOS 16.0, *)
    open var maxPhotoDimensions: CMVideoDimensions

(btw. this note is not present in the docs https://developer.apple.com/documentation/avfoundation/avcapturephotooutput/maxphotodimensions)

1. Enabling autoDeferredPhotoDeliveryEnabled means that for a 24MP capture, the system will call the photoOutput(_:didFinishCapturingDeferredPhotoProxy:error:) delegate method, providing a proxy object instead of the final image data.

2. According to the WWDC23 session "Create a more responsive camera experience," this AVCaptureDeferredPhotoProxy must be saved to the PHPhotoLibrary using a PHAssetCreationRequest with the resource type .photoProxy. The system then handles the final processing in the background within the library.

To use deferred photo processing, you'll need to have write permission to the photo library to store the proxy photo, and read permission if your app needs to show the final photo or wants to modify it in any way.

https://developer.apple.com/videos/play/wwdc2023/10105/?time=799

This seems to create a hard dependency on the Photo Library for accessing 24MP images.

My question is:

Is there any way to receive the final, processed 24MP image data directly in the app after a deferred capture, without using PHPhotoLibrary as the processing intermediary?

For example, is there a delegate callback or a mechanism I'm missing that provides the final data for a deferred photo, allowing an app to handle it in-memory or in its own private sandbox, completely bypassing the user's Photo Library?

Our goal is to follow Apple's privacy-first principles by avoiding requesting a PHPhotoLibrary authorization when our app's core function doesn't require access to the user's photo collection.

Thank you for your time and any clarification you can provide.