Facebook Graph API权限错误：iOS调用/{event-id}/attending无结果问题排查

Let me break this down for you—this is a super common issue with Facebook's recent API policy shifts, so you’re not alone here.

Why This Is Happening: Policy Changes & API Deprecation #

Facebook has been tightening up access to event-related data drastically over the past year, and that’s almost certainly what’s breaking your long-working feature. Here’s the key context:

• Permission requirements got way stricter: The /{event-id}/attending endpoint used to be accessible with basic permissions like user_events without much friction. Now, Facebook enforces:

  • For Page-owned events: You need the pages_read_engagement permission, which may require app review depending on your use case.
  • For personal events: The user_events permission is still required, but Facebook now mandates a full app review to activate it—you can’t just toggle it on in the developer dashboard anymore. If your app was using this permission without going through review, Facebook likely revoked it recently.

• Old API versions are retired: If your iOS app is still using a Graph API version older than v13, those endpoints have been fully deprecated. Newer versions (v13+) enforce the stricter permission rules, and trying to use outdated versions will throw permission errors even if you had access before.

• App mode mismatch: If your app was in "Live" mode before but got switched back to "Development" mode (maybe accidentally during a config update), you’ll only be able to access test data (events you own or test users). Production events will return empty data or permission errors.

Why Graph API Explorer & iOS App Behave Differently #

It all comes down to error handling:

• The Graph API Explorer is a debugging tool, so it spits out the raw, unfiltered error ((#200) Permissions error) to tell you exactly what’s wrong.
• Your iOS app probably has error-handling logic that catches the permission error and defaults to returning an empty user list instead of showing the actual error message. That’s why you’re seeing an empty list instead of the explicit failure.

Steps to Fix This #

Here’s what you need to do next:

1. Update your Graph API version: Check your iOS app code and switch to the latest stable version (as of 2024, that’s v18). Old versions are no longer supported and will throw errors.
2. Audit your permissions in the Developer Portal: Head to Facebook’s Developer Dashboard, go to your app, and check the "Permissions and Features" tab. See if user_events or pages_read_engagement are marked as "Approved". If not, you’ll need to submit an app review request explaining exactly why your app needs access to event attendee data (be specific about your use case—Facebook is strict about this).
3. Validate event privacy settings: Even with the right permissions, you can’t access attendee lists for private events. Test with a public or restricted event that your app has legitimate access to.
4. Fix error handling in iOS: Update your API call logic to log the raw error response instead of silently returning an empty list. This will make debugging way easier going forward.

内容的提问来源于stack exchange，提问作者János