System under control — how to automate integration tests

Nobody wants to discover a production service laying down and not working, or even failing to behave as expected, with errors and incorrect data processing. On one occasion, we — Bumble, the parent company operating Badoo and Bumble apps — decided to greatly reduce such inappropriate behaviour through the use…

PHP code static analysis based on the example of PHPStan, Phan and Psalm

As a company Badoo has been around for over 12 years now. We have a lot of PHP code (millions of lines of code) and there are probably still strings of code that we use which were written all 12 years ago. Some of them were written back in the…

Routing for iOS: universal navigation without rewriting the app

What’s wrong with navigation anyway? Almost every app has a navigation between different internal components and it seems like it shouldn’t be a problem. UIKit contains more or less convenient containers like UINavigationController, UITabBarController and a flexible way to present screens modally. We, as developers, just need to use the right tools. However, as soon…

Part 2: Deep Learning for Engineers

Introduction to Transfer Learning In this article, we use the concepts we saw in part 1 article to unleash the power of neural networks and the reason for their current popularity, namely their reusability. We learn how we can (partially) automate the feature engineering part and how this opens a new world of possibilities…

Catching bugs on a client

Our team develops several products, Badoo and Bumble, two of the world’s largest dating and connection applications. For both, we have a web version (desktop and mobile) and mobile applications (Android and iOS). With more than millions of users, it’s important for us to gather client-side errors, and for this…

Features, but faster: the life of an Android developer at Badoo

Practically speaking, my colleagues and I often need to test an idea as fast and as simply as possible. There’s no point spending lots of effort on implementation because we know that if an experiment proves unsuccessful, we are going to jettison the code in question. Here I will be…

Jira combats chaos: how to not lose tasks in development

In my previous article I talked about how we configured Jira to make work flow as convenient as possible and to ensure tickets provided exhaustive information. The aim of today’s article is somewhat different. Assumptions: You are developing and providing support for a complex programming product in use by several…

How we achieved a 6x reduction of ANRs. Part 2: Fixing ANRs

In the first part, we discussed what ANR is and what are the ways of tracking it. In this article, you will find information on what problems we found in our application, how we fixed them, and the results we achieved. Application Startup The first thing to do if you want to…

Intercepting and redefining modal presentation from a third-party framework

The Problem Some time ago, here at Badoo, we introduced a third-party library to cover our project needs. It was working well, except for one detail: it was presenting UI using iOS modal presentation (typical full screen view controller which is shown from the bottom of the screen), but according to our…

Achieving State Of The Art Results In Natural Language Processing

Part 2: ELMo, BERT and MT-DNN In my previous article I covered some of the fundamental concepts in NLP. This time, I will introduce ELMo, BERT and MT-DNN, architectures which leverage these concepts and have recently achieved some State Of The Art (SOTA) results on NLP tasks. Embeddings from Language Models (ELMo) An introduction to ELMo can be found in this…

Split Testing (A/B Testing) with Swift

Nowadays there are a million apps that solve users’ needs, so it is becoming hard to create something new or be better than market competitors. This has led to a situation where a lot of companies and startups are running experiments to find out which features are actually improving their…

When pigs fly: optimising bytecode interpreters

“No matter how hard you try, you can’t make a racehorse out of a pig. You can, however, make a faster pig.” — A comment in the Emacs source code. Everyone knows that pigs can’t fly — just like everyone thinks they know that bytecode interpreters, as a technology for…

MVI in Kotlin Multiplatform — part 2 (2 of 3)

This is the second in a series of three articles on MVI architectural pattern in Kotlin Multiplatform. In the article part 1 we reminded ourselves what MVI is and learned how to use it to write shared code using MVI. We defined simple abstractions like Store and View as well…

Reactive selfies with Camera2 API on Android — Part 2

This is part two of an article, where I show how you can use RxJava2 to build logic on top of asynchronous API. I chose Android Camera2 API as an example (and didn’t regret it!). This API is not only asynchronous, but also has hidden distinctive implementation features which are…

Mutation Testing in PHP: quality measurement for code coverage

How do you evaluate how good your tests are? Many people rely on the most popular score, the one everyone knows — code coverage. But this is a quantitative, rather than a qualitative metric. It shows how much of your code is covered by the tests, but not how well…

Part 1: Deep Learning for Engineers

Introduction Deep learning has become one of the most discussed topics in the Data Science community. It has long made sense for the Bumble team — the parent company operating Badoo and Bumble apps — to use deep learning on a multitude of tasks. With over millions of users around the…

How to move large-scale React UI-components codebase to TypeScript

Hi, my name is Ivan Grekov and I am a frontend developer at Bumble — the parent company operating Badoo and Bumble apps Our frontend team’s main responsibilities are to deliver new user interfaces and support existing ones across our different applications, mostly within Badoo and Bumble websites. At a…

Screen navigation in iOS

In this article, we will go through different ways of presenting screens in the iOS app. We will start with most straightforward cases and eventually go through some advanced scenarios. In a nutshell we will be adding more abstraction layers to make our screens decoupled and navigation testable by unit…

Design Tokens beyond colors, typography, and spacing.

In recent months, I couldn’t help but notice how many people (and companies) when referring to “design tokens” what they actually mean is colors, typography, spacing (and in some cases elevation, timing, and sizing). While this is perfectly true, I think a key part of the picture is missing: design…

Continuous delivery for your Kotlin Multiplatform library

As part of the Bumble family— the parent company operating Badoo and Bumble apps — one of my main projects was involved in the team that created Reaktive library — Reaktive Extensions on pure Kotlin. In the case of Kotlin Multiplatform I discovered that continuous integration and continuous delivery require…

High-Precision Time: how to use fractional seconds in MySQL and PHP

Once I caught myself thinking about time in databases and realised that I nearly always used time with one-second precision just because it was a common way to it, as well as because that was exactly what was written in manuals in lots of examples. Today, however, this level of…

Optical alignment for frontend developers:

How to align elements in user interfaces. Hi, my name is Ivan Grekov and I work in the front-end team at Badoo. My primary responsibilities entail looking after the user interfaces for a variety of projects. More specifically, this involves working with optical alignment of user interfaces. In this article, I’d like to share with you why…

Part 1: Dynamic Delivery in multi-module projects at Bumble

Dynamic Delivery is a technology which allows you to install and delete parts of an application while the application is working, in order to reduce the space it occupied. If there are functions not being used, what is the point of a user having them on their device? In part…

Dub-dub 2019: my take on what’s new at WWDC

In this article I share my impressions of the conference: scroll down for, not just read about important updates and an overview of the sessions, but also something on my own personal feelings, having spent time with a happy crowd of people chanting, “Dub-dub! DC!” and dreaming of shaking Tim…

From zero to Cosmos — Part #3

This is the story of how a small style guide that was first introduced under the radar, became so appreciated by both developers and designers that it finally became a complex unification project — a design system called Cosmos. From zero to Cosmos — Part #1 From zero to Cosmos —…