Ask HN: Is there any way for an app to detect all installed apps on iOS device?

I usually download apps by a referral from a friend. S/he says "X is so good, you should have it." and I immediately download the app. I believe friend referral is a great validation to create the initial incentive.

I see people share screenshot of their home screen to show the apps they frequently use. But it'd be nice to have an standalone app (maybe there is, I couldn't find) in which you can see all the apps that specific user is currently using. And get notified when someone you trust just downloaded the app, like "pg is just downloaded XXX."

I tried to find a solution, but I couldn't find a decent one. I think Apple does not allow to get such data from user's device. I tried to get the user's purchase history, but this also seems impossible to proceed on.

Any ideas or possible hacks to solve this problem ? I just want to brainstorm on this together.

Thanks.