I got frustrated hearing about phone snatching in London - thieves grab unlocked phones and immediately access banking apps, messages, photos. Android has had Theft Detection Lock since 2024 while iOS still has nothing.Apple s Stolen Device Protection delays password changes but doesn t touch the content of an unlocked phone. So I wired a few things together:- CMMotionManager at 20Hz for grab detection. I tried CMMotionActivityManager first - total waste of time. It reports Unknown instead of Running , flickers between states and has a much bigger delay.- FamilyControls + ManagedSettings for system-level shields. As there s no way to lock the phone programmatically I came up with the idea of locking the desired apps. The shield overlay persists after force-close and there s no way to dismiss it without opening the app and passing Face ID.- Background location at kCLLocationAccuracyThreeKilometers to keep the accelerometer alive when the app is suspended. The data is never transmitted — coordinates are stored locally only when a snatch triggers so you can see where it happened.Main weakness I should mention: deleting the app removes the shields. You can mitigate this with Screen Time passcode + disabling app deletion in Settings, but it s not automatic.No analytics, no tracking, no network calls.