Convenient Screen Locking with JB LockNow
JB LockNow is a free personalization app developed by iggy.dev for Android devices running on Android 4.1 (Jelly Bean) and above. With this app, you can easily lock your screen with just a swipe up from the Navigation Bar. On Android 6.0 (Marshmallow), you can set JB LockNow as your default assist app by going to App Settings > Set Default Assist App > Assist App > JB LockNow after a long tap of the Home button.
One of the unique features of JB LockNow is that it allows you to replace Google search, enabling you to turn off the screen with the same gesture. It also supports shortcuts, giving you the ability to turn off the screen at any time. You can rest assured that your privacy is protected as you can disable the Google search from the configuration and remove the default apps.