Backdrops has a massive collection of awesome wallpapers and it is very frequently updated with new content. You’ll find different kinds of wallpapers in the app, and you can browse by categories, browse by tags, or just browse the ones featured on the main screen. You’ll possibly never run out of new wallpapers in there.
Just like on Android, the iOS app is available for Free on the App Store. There’s an optional $3.99 upgrade to “Backdrops Pro” that enables an ad-free experience, unlocks exclusive collections and supports the developers.