When’s there gonna be an IOS app made?

Id guess never. There's a pretty high bar for entry to the apple market place, I don't think sw would want to overcome all that.

I think the app just uses a browser.

For example, SW started failing on Chrome on my old Android phone. So I installed the SW app. It asked me to update Chrome. I could not.

Later, I figured out how to update Chrome (I needed to use WiFi not mobile data -- strange). Yet now I just use Chrome again. I have not yet tried the SW app again.

Its been promised for years

No need. Works fine on browser

Just use it on safari

https://similarworlds.com/help/42-How-do-I-install-the-SimilarWorlds-Mobile-app

Until the IRS approves it