2021 is a very exciting year for developers who use Expo to build their mobile apps. The team with the assistance of the Software Mansion open-source team have been working hard on making React Native app development quicker and simpler; as a result of this progress, many statements on…


Kotlin is an awesome language, but its “syntax sugar” can sometimes be confusing. Although this particular thing is mentioned in the documentation, it’s easy to miss. Let’s start with an example:

We have a class AspectRatioScreen with one property, which defaults to old good 4:3. Then we have ResolutionScreen with…


Over a year ago I wrote an article about a kind of hacky way to use react-native-firebase in Expo app. But things have changed significantly since then. In this article, I’m going to show you the new, much easier way to do this. …


When writing applications in Node, you often need to write or read the contents of a file. Node.js provides a fs library dedicated to this purpose. But how do we deal with the filesystem when testing our code?

I’m going to present two approaches to this problem – by mocking…


When you are making a LED project, you often need to control it using PWM. For RGB projects you need at least 3 PWM channels. If you wanted to control 10 individual RGBs, you need 30 PWM channels, unless you use external driver IC or digital LEDs like WS2812.
Most AVR…


Raspberry Pi 4B has one well known issue — it doesn’t power up when plugged using some USB-C cables. It may work with old USB-C to USB 2.0 cable, but, for instance, with original MacBook charger it doesn’t. …


I got used to using Expo. It has many useful and ready to use libraries and an awesome Client app. Recently I’ve been working on React Native app, which used Firebase Cloud Firestore as the main database.

Update 07/2021: This article has become outdated and the solution described …

Bartłomiej Klocek

Enthusiast of electronics and all kinds of software development — from web apps to embedded systems. Expo open-source contributor at Software Mansion.

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