LG's new Knock Code feature is one cool way to lock and unlock your device if you're using one of the compatible LG devices that has it built in. For the rest of us though that don't have one of those phones there is an alternative to at least locking your device with a similar function, by using an app called Knock Lock. It's still quite a bit different than Knock Code, as you can only use it to lock your device and you get no similarities other than that, but it's still pretty useful as locking your phone from the display in this manner just seems more natural.
Knock Lock as stated above will only lock your device, it will not unlock it right now but that doesn't mean that it wont become an included feature down the line. The app is pretty easy to use and it's simple and straightforward. All you have to do is install Knock Lock which is completely free, than once installed open it up and set your parameters,(first you should be prompted to allow the app administrator rights) then you can set how big the transparent overlay box is(width and length) and where the box is placed on screen. For me personally it feels the most natural more towards the bottom right side of the display as I hold my phone in my right hand and that is within the area my thumb travels on the screen.
For those worried if this will effect battery life, the apps developers say that it shouldn't effect battery life to a noticeable extent-only affecting about 0.1% as it sits in the backgroud- which is good news for anyone who may have poor battery life as it is. Knock Lock is simple, easy, and understated, and we expect this to be a fairly popular app in no time. Once everything is set in place, you can knock the designated spot to put your phone to sleep. It seems to provide a lag free experience and put the phone to sleep immediately, so all around it feels no different than if you lock your phones display with the power key.