What happens to your data after deleting the app from iPhone device?

Before getting into the what happens with the data on device after app is deleted, let’s understand why it’s been stored locally on device.

Why data stored locally on device?

Developers store some data on devices for faster response and avoid making multiple calls to retrieve the data. If data is static or changes rarely, it helps user to get faster response for that kind of data. Also user specific data like username is also stored on device so user don’t have to enter that data every time. There are multiple ways to store the data on device and that’s another article all together.

What happens when app is deleted?

When user decides to delete the app from the device, App gets wiped out from the device. Also same time any data stored by the app locally gets wiped out. So basically all the history, data, settings get deleted. When user download the app again, it’s like first time user.

Why Facebook still shows Continue as last logged in user?

But some apps like, Facebook, Tinder are more sticky than standard delete operation. When user delete the Facebook app and download again, it shows last logged in user with option to tap on the user and continue using the app where you left last time. So what’s the trick here?

Facebook and similar apps have created sticky way to provide user faster experience. They are storing user device id (UID) along with user credentials. So when user opens the app, Facebook check if there is any account associated with device id (UID) and provide the access token to the app so user can login quickly. So basically there is no data on device when user opens the app, but previous usage makes facebook to provide quicker access next time.