Printoid is not available for iPhone users. The only versions available are made for Android users, for the only reason that… I am an Android developer 😉
But there is a very very good alternative on iOS: OctoPod!
This app has been developed by Gaston Dombiak, and it is open source on Github. It has amazing features and works flawlessly! Moreover, the app is still actively developed by its developer and the community.
You can download it for free on the Apple AppStore:
The app also has an OctoPrint plugin to empower the experience.
You can follow the OctoPod project on Twitter.