system-wide password manager in iOS and OS X
I personally use (and obviously prefer) 1Password. This is not cheap, but does regularly go on sale for much discounted prices.

1Password will do everything you want and more. It works across iOS, macOS, Android and Windows. You can watch a video highlighting its features. And, you can also try it out for free.

And of course, it offers extensions for Safari, FireFox, etc. You can also download it directly via the Mac and iOS App Stores.

Disclaimer: I have no affiliation with 1Password whatsoever.