Mastodon now has an official app for iPhones, you can get it from the App Store:
(The app is FOSS, the source code is at https://github.com/mastodon/mastodon-ios )
The official app is aimed at new users who aren't familiar with the Fediverse. It streamlines the signup process and hides some features such as the Federated timeline.
However, because Mastodon is built on open standards, it has lots of unofficial apps too. There's a complete list at:
@feditips did they pick a default instance? I found picking an instance without yet being on an instance was the biggest barrier to entry :/
There's a signup wizard which lets users pick from the same instances as listed on https://joinmastodon.org (i.e. committed to long term support, have a strong anti-hate code of conduct etc).
I agree that defaulting to a single instance would be easier, but that would cause its own problems with centralisation.
Discover & explore Mastodon with no ads and no surveillance. Publish anything you want on Mastodon: links, pictures, text, audio & video.
All on a platform that is community-owned and ad-free.
Hosted by Stuxhost.