MyCalendar TopSecrete is not a calendar app at all but a way to hide your personal images, videos, and more on your iPhone. The app uses a calendar overlay and a clever password system to lock out those images and "hide" them behind a facade that most people won't see through, over a casual glance. The setup process can be a bit confusing, but it generally works quite well.
When you open the app for the first time, there is no indication of what you're supposed to do. There is a blank calendar onscreen with no events and an options menu hidden inside of an ad at the bottom of the screen. This is a good thing as someone else using the app will never suspect that it is really a hidden vault for your personal data. Tap that options menu, though, and you can find your password, reset it, and get started. To enter a password, you'll tap it into the dates on the calendar and then enter into the back-end where you can load new images or videos for safekeeping. The entire process is seamless, though the interface is a bit dated and lacks polish.
MyCalendar TopSecrete Free isn't the most intuitive app, and it doesn't look particularly good, but it does the one thing it promises -- it hides your photos and videos in a way that few will be able to find them. That alone makes it worth checking out if you need a third-party app that will keep your personal photos and data safe on your iPhone.