AppLock‏

Smart App Lock is the best application lock program that will help you save your applications, private photos, messages and more in the best and easiest way. Get the perfect guard for your phone and nobody will disturb your privacy
The most important features of Smart App Lock:
☆ Protection in unique ways: Close the applications you use: Contacts, Messages, Email, Gallery, Phone Settings, Twitter, or Facebook easily, safely and smartly.
Gallery photos can be locked and protected
- Lock Facebook.
- WhatsApp lock.
- Lock files.
Lock all your programs and files
- Lock applications more than one application
- Apply lock protection at the same time

Give your phone complete protection.
AppLock uses Device Administrator permission. (only used to prevent AppLock from being uninstalled)
AppLock uses the Accessibility service.
To enable power saving mode, allow accessibility services. The service is only used to reduce battery usage, improve unlock efficiency, and ensure that AppLock works stably. Don't worry, AppLock never uses the service to access your data.

And there's more in the Smar smart locker app