Defndr – SMS Spam Blocking on iPhone

Wrestling with Apple's IdentityLookup framework

Defndr is a minimal iOS app that filters out SMS spam using Apple's IdentityLookup framework — or at least, that was the plan.

The problem? Almost no documentation. The official docs were outdated, vague, or straight-up wrong. No examples, no clear guide to what triggers filters, how often they're called, or how your extension is supposed to communicate with the host app. So it became trial and error. Guess the config. Guess the entitlements. Hope it works.

$ developer.log
Does this key need to be in the app target, the extension, or both? No clue.

I reached out to Apple through feedback and dev forums. Weeks passed. Silence. Eventually got one vague response that contradicted another thread. It's wild how much of iOS development is just guessing — and hoping the system decides to work.

Anyway, after some swearing, a few TestFlight rounds, and lots of NSLog breadcrumbs, Defndr is now silently filtering spam in the background — when iOS feels like calling it, that is. I will see about when to release it on the app store, no rush on it anyway and I want it to work properly and reliably.

Published [January], 2025 by Dro1d Labs