Use a physical, NFC-capable iPhone (NFC does not work in Simulator) and an official FocusLatch Key. Each key carries a cryptographic signature bound to its chip; generic store-bought NFC tags and copies are rejected on purpose — a key should be a deliberate object, not something you can re-buy in a weak minute. Hold the top of your iPhone flat against the key and keep it still.
Check three things on the home screen: Screen Time access is allowed, at least one app, category, or website is selected in the active mode, and a Focus Key is registered. Then tap Begin focus — the shield appears over blocked apps immediately.
Long-press Emergency at the bottom of the locked home screen and confirm. After the waiting period you chose in Settings (15 minutes, 1 hour, or 8 hours), the Unlock now button becomes active. The countdown continues across force quit and app restarts, and changing the system clock does not shorten it.
While focus is running you can add apps, categories, and websites, but not remove them. Removing is possible again after unlocking with your key.
No. The blocking is enforced by iOS itself; FocusLatch does not run in the background.