Here’s a polished Apple Developer Forums post you can use. I removed personal identifiers such as email, Person ID, Team ID, and DTS Case ID because the forums are public. The post is based on your DTS request and Apple’s response directing you to ask in the Developer Forums. 
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Title
Supported public API to open containing iOS app from Share Extension for image/PDF share sheet imports
Tags
iOS Share Extension UIKit App Intents Uniform Type Identifiers
Post Body
Hello Apple Developer Forums,
We are building an iOS app that needs to receive images and PDFs shared from the system share sheet. The sources include Screenshots, Photos, Files, and third-party apps.
The desired user experience is similar to apps such as ChatGPT or Claude: when the user taps our app in the share sheet, the main containing app opens and starts importing or uploading the shared image or PDF.
We are trying to understand the supported public API for this behavior.
What we have tried
CFBundleDocumentTypes
We added document type support for:
public.image
public.png
public.jpeg
public.heic
public.heif
com.adobe.pdf
This works for some document-open flows, such as opening files from Files or Photos in certain cases.
However, it does not make the app appear reliably as a share target from Screenshot Share or from some third-party app share sheets.
App Intents
We tried using App Intents with IntentFile and:
static var openAppWhenRun: Bool = true
However, this does not seem to create a general-purpose share-sheet receiver for arbitrary image or PDF NSItemProvider payloads.
Share Extension
We also implemented a Share Extension that:
Receives the shared NSItemProvider.
Stores the image or PDF in an app group container.
Attempts to open the containing app.
However:
NSExtensionContext.open(_:completionHandler:)
does not appear to foreground the containing app from a Share Extension in the way we need.
We also tested responder-chain openURL: trampoline approaches, but those do not work reliably and appear to be unsupported as a public API contract.
Questions
Is there a supported public API for an iOS app to appear as a share target for arbitrary image/PDF NSItemProvider payloads and then directly open the containing app?
If apps such as ChatGPT or Claude appear to switch directly into the main app from the share sheet, is that behavior achievable using public APIs available to third-party developers?
If directly opening the containing app is not supported, is the recommended design to perform all upload/import work inside the Share Extension itself?
Are App Intents intended to support this kind of share-sheet attachment import flow, either currently or in a future iOS version?
Reproduction Steps
We created a focused sample project to reproduce the issue.
Build and run the app on a physical iPhone.
Leave the app installed.
Capture a screenshot.
Tap the screenshot thumbnail.
Tap the Share button.
Choose the app’s Share Extension from the share sheet.
Observe that the Share Extension receives the image payload.
Attempt to open the containing app from the extension.
Expected Result
The containing app should foreground and receive a URL or other handoff signal indicating that a shared file is available for import.
Actual Result
The Share Extension receives the image payload and logs the provider type identifiers, but the containing app does not reliably foreground.
NSExtensionContext.open does not provide the desired transition, and responder-chain URL-opening workarounds do not appear to be supported or reliable.
Minimal Question
For image/PDF imports from the iOS share sheet, should the supported implementation be:
Share Extension receives the file → Share Extension performs the upload/import itself
rather than:
Share Extension receives the file → Share Extension opens containing app → Main app performs upload/import
Any guidance on the supported architecture would be appreciated.
Thank you.