Share Extension: `NSExtensionActivationRule` with `public.url` Not Showing in Share Sheet

I am building a share extension in iOS that allows users to share a URL (e.g., from Instagram) to my app. My extension works perfectly when I use:

<key>NSExtensionActivationRule</key>
<string>TRUEPREDICATE</string>

However, this gets rejected by Apple when I try to upload the build to TestFlight with the following error:

Invalid Info.plist value. The value for the key 'NSExtensionActivationRule' in bundle ... is invalid.

To comply with Apple's guidelines, I am trying to use a specific activation rule for URLs. My current Info.plist looks like this:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>NSExtension</key>
    <dict>
        <key>NSExtensionAttributes</key>
        <dict>
            <key>NSExtensionActivationRule</key>
            <string>
                ANY NSExtensionItems.attachments.contentTypeUTI == "public.url"
            </string>
        </dict>
        <key>NSExtensionMainStoryboard</key>
        <string>MainInterface</string>
        <key>NSExtensionPointIdentifier</key>
        <string>com.apple.share-services</string>
    </dict>
</dict>
</plist>

However, with this rule:

The share extension does not appear in the share sheet when I try to share a URL.

Debugging logs confirm that the attachment type is public.url

Attachment Type Identifiers: ["public.url"]

What I Have Tried:

• I used NSExtensionActivationSupportsAttachmentsWithMatchingTypeIdentifiers like this:

<key>NSExtensionActivationSupportsAttachmentsWithMatchingTypeIdentifiers</key>
<array>
    <string>public.url</string>
</array>

Result: The extension still doesn't show up.

• I ensured the App Group is correctly configured for both the main app and the extension target.
• I cleared caches, deleted the app from the device, and rebooted the device.

Working State (but Rejected by Apple):

If I use:

<key>NSExtensionActivationRule</key>
<string>TRUEPREDICATE</string>

The extension appears correctly in the share sheet and works as expected, but Apple rejects it during validation (when I try to upload my app to TestFlight).

Questions:

1. Why doesn't my share extension appear in the share sheet when targeting public.url with a proper NSExtensionActivationRule?

2. What is the correct and Apple-compliant way to configure NSExtensionActivationRule so the extension appears for URLs and passes TestFlight validation?

After much trial and error, I finally got the app to show up in the share menu when sharing URLs from apps like Instagram and TikTok. The solution involved adding the NSExtensionActivationSupportsWebURLWithMaxCount key, which I initially overlooked.

Apple’s documentation on NSExtensionActivationSupportsWebURLWithMaxCount is subtle and not always clear about how it complements NSExtensionActivationSupportsAttachmentsWithMatchingTypeIdentifiers.

I had assumed (wrongly) that public.url alone would suffice in all cases since it’s a universal UTI. However, the behavior of host apps like Instagram treating URLs differently exposed the flaw in that assumption. Adding NSExtensionActivationSupportsWebURLWithMaxCount explicitly to the Info.plist made all the difference.

Here’s the full Info.plist that finally worked:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>NSExtension</key>
    <dict>
        <key>NSExtensionAttributes</key>
        <dict>
            <key>NSExtensionActivationRule</key>
            <dict>
                <key>NSExtensionActivationSupportsAttachmentsWithMatchingTypeIdentifiers</key>
                <array>
                    <string>public.url</string>
                </array>
                <key>NSExtensionActivationSupportsWebURLWithMaxCount</key>
                <integer>1</integer>
            </dict>
        </dict>
        <key>NSExtensionMainStoryboard</key>
        <string>MainInterface</string>
        <key>NSExtensionPointIdentifier</key>
        <string>com.apple.share-services</string>
    </dict>
</dict>
</plist>