Photo Locker is a camera app that automatically adds any image you take to a hidden, password-protected folder on your iOS device. As a result, it offers a bit more flexibility than a privacy app without a camera, though there are some issues here with the setup and accessing those images once they are stored in the password-protected camera roll.
When you open the app for the first time, you'll find a camera app -- snap photos and they will be instantly saved to your photo library. You can then set a password with the button on the bottom of the screen and move any image you take to the secure photo library in Photo Locker. The password is full-alpha-numeric, which offers better protection than some of the PIN-based passwords on other security and privacy apps on the App Store. While the interface is a bit rudimentary in some places, the app is very quick and the process of loading and viewing your hidden images takes almost no time at all.
If you want a hidden storage compartment on your iPhone to store and protect your images from prying eyes, then Photo Locker is a great option. It's easy to use, quick loading, and offers the basic protection you need to keep your images private. There are no options for storing notes or other items and the interface is very basic, but for the core function, it works quite well.