IPHONE SETTINGS
How to lock an app on iPhone
Searches for app lock often expect a padlock on the icon. On iPhone the lock is Screen Time: the app you pick cannot open once the limit hits. You can lock a single app in Settings without installing anything.
What lock means here
The home-screen icon stays. After the cap, it greys out and opens to a limit screen.
This does not hide or delete the app. It is a switch that stops you opening it right now.
Lock one app
Settings > Screen Time > App Limits > Add Limit. Pick the app itself, not a whole category — YouTube only, Instagram only.
Set a cap. If you want it blocked now, keep the cap short. Starting at zero often trains other paths; a short limit is a better first move.
Set a Screen Time passcode. Without it, Ignore Limit turns the lock off.
A cap versus Downtime
App Limits are a daily ceiling. You use the app until the cap, then it locks.
Downtime locks most apps on a clock — evenings or the commute. Leave Phone and Maps in Always Allowed.
If one app is the problem, use App Limits. If the whole evening is, use Downtime. One is enough; both is fine.
Where the lock gets thin
Use a code only you know. Birthdays come off quickly.
The same service can still open in a browser. The lock makes that home-screen icon harder. It does not switch the internet off.
Screen Time does not keep a balance of protected time. The report only shows what you used.
If you want those minutes kept
Dopamine Bank is an upcoming iPhone app that shields the apps you pick and keeps the time as a balance. You can already lock a single app in Settings today.
If you want locked time to add up
The App Store listing is being prepared. This does not diagnose or treat addiction.