App Tracking Transparency

App Tracking Transparency is the iPhone permission prompt that asks whether an app may track you across other companies' apps and websites.

In 2026 none of this has loosened. When someone opens your app, iOS shows Apple's own popup with two choices, Ask App Not to Track and Allow. Only if they tap Allow does your app get the device advertising ID it needs to tie a person to the ad they saw.

Say 100 people install after clicking your Meta ad. If 25 tap Allow, you can trace those 25 back to the exact ad, audience, and spend in Ads Manager. The other 75 still count as installs, but the person-level trail is gone. Open your own attribution dashboard and read the opt-in rate; that share is the ceiling on how much of your iOS spend you can measure the old way.

You do not get to skip the prompt or word it to nudge a yes. Apple reviews the copy, bans incentives, and rejects apps that read the ID before showing it, so a low opt-in rate is something you plan around, not something you talk your way out of.

On iPhone, tracking is a favor the user grants, not a default you inherit.