Ask HN: How does the evercookie on iphone/ipad work?

Some sites are placing evercookies on Safari on iphone and ipad that are not removed with normal steps. Respawning instantly somehow.

Sites include Western Union, BioLite, NewEgg ... how are they doing this?

Google cookies don't show, but search history persists, even if you change IP. Eventually after repeating the delete a few times and killing the Safari app, the Google search history will stop showing.

Thinking these are two different exploits being used to keep state.

Been in place for a while. Just getting around to asking here.

How is it being done? An exploit or a feature?