People who love to click lots of photos. Some photos are very private or they are unique. They can’t afford that somebody can see. So they need to install Leo privacy guard. As this application is new so it is according to today’s need. We can lock whole mobile but every time when we use it requires unlocking. So it is time consuming. But by installing this application we can lock applications and hide photos while full phone is open to use.
I think the app is exciting.The app will definitely be popular.
I suggest you to try Leo Privacy Guard that can secure you phone and data and also keep your phone safe from annoying snoopers and prying eyes. Leo Privacy Guard hide your photo/videos and secure your phone call.
As said by many others, Leo Privacy Guard is definitely a great app to lock your files and other data. You can hide almost everything with the help of this app. Give it a try! 
There are so many application available in market like
LEO Privacy Guard - Lock&Boost
AppLock
CM Security Antivirus AppLock
Smart AppLock (App Protector)
Smart AppLock (Lock Apps)
Advanced Protection
but i think LEO Privacy Guard is best have 999,000 + Downloads and even good review i think you should go with that
I agree with @JosephCarter and @thomaswiggins800. Leo Privacy Guard is probably your best option. It gives you complete control over all aspects of your phone. You can hide virtually anything and you have the option to password protect your applications.
Honestly I’m surprised that it’s not a paid app. Currently it’s free.
leomaster app locker is used for security
Leo Privacy Guard, would be the best security app for securing your device.