Is there a way to limit Facebook use on iPhone and iPad?

I use "Stayfocused" on my Macbook, but it's a Google Chrome extension and Chrome isn't supported for mobile platforms.

Likewise with "Leechblock", a Firefox extension. Good for Macbook, but apparently not supported for iPad/ iPhone.

I can't find any apps in the store that limit Facebook.

Surely there must be something I'm missing? I imagine I'm not the only one searching for something like this. There seem to be dozens of versions of this idea available for desktop computer, but it seems a bit pointless if you can circumvent them by just picking up the phone or iPad. Any tips gratefully appreciated!