PhotoLock is a security tool that protects photos and videos taken on iOS devices with a four-digit password. It is free to use and ad-supported, and while there are a few additional features that would be valuable, the app, itself, is functional, so it can be very useful for images and videos you'd prefer not to share on your iOS device.
PhotoLock requires a pin number when you sign in. It should be something you'll remember or you may not be able to access the app again later. You can enter an e-mail, as well, to remind you of the pin, but PhotoLock makes it optional. Photos are added to albums and can only be accessed when you enter the pin. The photos are saved, allowing you to delete them from your public photo stream. PhotoLock also has a fake passcode function so that you can pretend to enter in a pin successfully but see no photos, as well as an e-mail option to send any photos in the application to your e-mail address. It doesn't have the option to save back to your iOS device, unfortunately, but the e-mail function provides roughly the same benefit. The interface is well designed in that you can access your images, log out quickly, or share anything from one screen.
Many people keep secret photos on their iOS devices and risk their becoming public. While PhotoLock isn't the perfect app for privacy, it does have thoughtful features, no apparent bugs, and provides an additional step for keeping your private photos secure. Overall, it is not a bad choice for those that need a way to keep their images and videos a secret.