Securing Folders or files in Iphone (iOS7)

Thanks God in a couple of days I am getting rid of this crap Blackberry to switch to Iphone.
I've started browsing for some good apps related to security, but there is a huge world out there and I am struggling to understand which fits best my needs.
Basically, I need to store in the phone some PDF's with sensitive information, which I would like to protect even beyond Iphone hardware encryption.

Also a good password manager (maybe even with some "wallet" features, like credit card storing, etc.) is needed.

I trust more you guys than the several listing on the web, usually leveraged by ads and so on.

Anything you recommend?