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Case Study: PhotoFolder app guarantees your privacy

25.11.2016 Alexa Klimow
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Case Study: PhotoFolder app guarantees your privacy

Here, we would like to present one more project we’ve done for our customer. PhotoFolder is the application keeps your documents locked and let you view them privately


Business: B2C
Development Environment: Xcode
Technology: Objective-C, MVC, Realm, Reactive
Platform: iOS 8.0+

The Challenge

The client wanted to get the app that locks your private files (audio and video content). The app has to be encrypted and be able to sync with more than one device. The access to the private data should be fulfilled only to the authorized users and protected in case other users may want to reach it. The app should have other premium features (advertising banners removal, flip to hide feature, fake pin, break in alerts, etc.) and be able sync with cloud.

System Highlights

For the database our mobile developers picked up Realm Mobile Database and with its help we realized the logic of synchronization. This kind of database also allowed the developers to speed up the overall work on the application and enable the pin screen feature being active each time the app closes. To unblock the screen the user has to use Touch ID option or insert the pin. The developers also supplied the app with the fake-mode that requires the fake password. Once this scenario is performed, whoever enters the fake password will see the standard audio and video content, the locked one goes to invisible mode.

The auto-renewable subscription was brought to life with the help of the remote server. The encryption algorithm was chosen to be AES-256+SHA2 that supports 64-byte encryption key. To verify the level of encryption we used SHA-2 HMAC protocol. To implement Touch ID option a standard Local Authentication framework was used. Touch ID prevents the user from entering the password every time the app is in the background mode.

Key Features

  • Ability to store the data on Realm Server;
  • Data syncing;
  • Provision of standard folder to keep photo and video content;
  • Folder creation;
  • Ability to save photo and video content to the chosen folder;
  • Files import from the photo roll;
  • Photo and video viewer;
  • Files export and deletion, easy transfer from folder to folder;
  • Folder configurations (cover selection, folder name editing, password set up);
  • Application configuration (password editing, email, default folder to save photo and video, in-app purchase completion and restoration);
  • In-app functionality: the usage of auto-renewable subscription mechanism with its own server to store the user’s account;
  • Premium features are valid only after the purchase is complete. Premium features include advertising banners removal, flip to hide feature, fake pin, break in alerts and cloud synchronization;
  • Ability to block the app for 5 minutes when the wrong password has been entered for 3 times.


As the result, we have developed an easy-to-use application that locks the private audio and video content and provides the high level of security. The locked content is encrypted and only the appropriate method of screen unlock provides a legit access to it. The choice of the Realm database gave us an opportunity to store it in the cloud through iCloud, Dropbox, and Amazon. One of the means to unblock the screen and get access to the locked folders is Touch ID. We also gave the app the functionality to be synchronized with many devices.

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