The good news is that a developer with the handle greensnow has released two jailbreak tweaks called Icon Passcode and Folder Passcode on Cydia that allow you to not only passcode protect apps, but also passcode protect iOS folders.
After installing Icon Passcode, you will be prompted to set the master passcode via the Settings app (Settings -> Icon Passcode). You can then individually enable passcode protection by tapping on the On/Off toggle (Settings -> Icon Passcode -> Locked Applications).
The jailbreak tweak also allows you to lock the app switcher to ensure someone cannot access the recently opened apps via the app switcher.
Just like the Icon Passcode, after installing Folder Passcode, you will be prompted to set the master passcode via the Settings app (Settings -> Folder Passcode).
To passcode protect a folder, you need to tap and hold on the folder to put it in wiggle mode, then replace the title of the folder with “[lock]” and then tap “Done. You don’t need to worry about the title of the folder as it will revert back to the original title and also passcode protected the folder.
Check out the video walkthrough of Icon Passcode and Folder Passcode below:
Icon Passcode and Folder Passcode are both available for free on Cydia via the ModMyi repo.
As always, let us know what you think of the jailbreak tweaks in the comments below.