I believe this works on Android in general, but I tried on GrapheneOS. Open the Settings app. Tap Security & Privacy > More security & privacy > App pinning. After that is enabled, if you want to pin an app, open it, swipe up into the recent-apps view, tap the icon of the app above the preview pane, and select "Pin".

The feature is buried a bit. I believe this is because it's more of a best-effort protection. The settings page itself says:

"When an app is pinned, the pinned app may open other apps and personal data may be accessible. If you want to securely share your device with someone, try using a guest user instead."

Both Apple and Android have this feature preloaded. On Apple it’s called Guided Access and is three taps of the power button if enabled. On Android I’m not sure but I do know it exists (edit: it’s called App Pinning)

On iOS you can also disable specific actions and even select areas of the screen you want to disable touchscreen usage over.

This feels like a social problem, not a technological one, and I am unconvinced that a technological solution will work here.

If the worry is that the cop you hand your phone to will take more access than you want, then attempting to limit that access is probably not going to work out the way you want.

A more effective solution would be better legal protections.

Unless I'm misunderstanding, isn't that what app pinning on android is?

https://support.google.com/android/answer/9455138?hl=en

The feature I want most is NOT sending a notification to the app whenever I take a goddamn screenshot.

Well, iOS does already. „Guided Access“ is exactly what you described.

I had an Android phone circa 2018 (Samsung S8) that had this feature: it was called "App Pinning" and people could only navigate inside the pinned app until you unlocked your phone like you usually would.

Edit: I am now an iOS user since 2022, and I only learn about "Guided Access" from other comments haha

App pinning exists on Android already, it's extremely useful if you're handing over your phone to your child to just watch netflix or whatever :P It's just extremely unintuitive, I had to google where it is.

I need this for when my child gets a hold of the phone.

App pinning is a thing on Android already, although I don't know how well it's supported in all the devices.

> This means it would be more easily abused if you're using biometric unlocks, yes, but by no means does it make the feature useless. And it normalizes a level of trust between individuals which is appropriate, but impossible, in many situations.

Here's the problem. By being abusable, it falsly normalises a level of trust. I.e. it deceives the user into trusting it.

iOS has a hidden album but the UX isn't great: https://support.apple.com/en-us/104987

This is a silly article. Both Android and iOS have exactly this feature.

GrapheneOS has this.

> Android and iOS should have a system-level ability to lock focus on the active application.

iOS already has this, it's called Guided Access and you can access it by triple-pressing the power button... it even lets you set up areas of the screen that can't be pressed.

How about a guest unlock where you can lend your phone to someone to do basic web browsing or make a call, but they can’t see any of your data.

Entirely logical, but phones seem designed to be tracking/surveillance devices.

"Android and iOS should have a system-level ability to lock focus on the active application. This would mean you could open a concert ticket, a photo, or your digital insurance record (which is a VERY BAD IDEA to hand to a cop without this feature), guest-lock your phone, and hand it over without any worry that someone could start opening other apps to look for things you didn't want to show them."