Safari iOS PWA Data Persistence Beyond 7 Days

Question

Created Jul ’22

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We need a web app that can operate offline (in cars and small aircraft), hence a need to store data, including a lot of map tiles, and not have it disappear after seven days (due to ITP restrictions).

I have read articles suggesting that a PWA (Progressive Web App) launched from the Home Screen does not have the persistence time limit, but cannot find documentation from Apple stating this one way or the other.

Also, can one store more than 50MB if using IndexDB?

Is there a definitive answer to either issue?

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Answer 1

cupocoffee OP

Oct ’22

Same issue. Lack of docs around this is pretty terrible. The best I've found is this (search for 7-day): https://webkit.org/blog/10218/full-third-party-cookie-blocking-and-more/

Additionally, Safari desktop doesn't appear to support Add to Home Screen...so that seems to imply that people using a offline first web app on Safari Desktop will always be at risk for data loss. Unacceptable!

I have experimented with using the StorageManager "persist" option with Safari Desktop in order to mark persistence as "protected". However, it appears this gets reset when the browser closes and again there's a lack of documentation so it's not even clear if this would help protect against the 7-day ITP timer.

Without more documentation and clear direction from Apple, I'm basically forced to tell my users not to use Desktop Safari :(

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Answer 2

molnarmarton OP

Feb ’23

Yes, Home Screen apps don't have this limitation, here are the official docs: https://webkit.org/tracking-prevention/#intelligent-tracking-prevention-itp

As for the persistence permission: there is no official info on whether this is "stronger" than ITP (apart from a Twitter thread at /firt/status/1592326461050204160), but our experience is that it does protect data from being deleted. However, as you mentioned, it has to be requested every time your app is opened.

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