Backstage Blog

• Mobile
• Xbox
• Authentication

A method for signing in to a device that doesn’t have a keyboard

When we were developing our SoundCloud app for Xbox One, something became very obvious during usability testing: signing in with a game controller really sucks. Entering text requires navigating a virtual keyboard to individual letters, numbers, and characters one at a time – such a nightmare! Plus, letters, numbers, and special characters are spread across three screens. The more secure your password is, the worse the experience is.

• React Native
• Mobile

About a year ago we faced an interesting question at SoundCloud: can we build SoundCloud Pulse — our app for creators — with React Native? Is a five-month-old technology mature enough to become part of SoundCloud’s tech stack?

• Android
• Mobile

Last week, we open-sourced LightCycle, an Android library that helps break logic out of Activity and Fragment classes into small, self-contained components called LightCycles.

Components that typically need to be aware of Activity and Fragment lifecycle events include presenters, UI tracking code, input processors and more. We’ve been using LightCycle extensively in the SoundCloud Music & Audio and SoundCloud Pulse apps over the last year.

• Android
• Mobile

In part one we described how running into Android’s method limit may leave you unable to build, and offered strategies you can employ to make your app fit into a single DEX file. In this part we share an alternative option: using multiple DEX files.

• Android
• Mobile

At SoundCloud we have been building for the Android platform since 2010. Much has changed since then: the team has grown, the list of features has grown, and our audience has grown. Today, eight engineers are working full time on the official SoundCloud app, across various areas, with contributions pouring in from other parts of the organization. Due to the growing complexity and number of contributions, the app’s size has grown substantially. Currently the app consists of approximately 1200 Java source files, not counting tests, containing approximately 86000 lines of code. This doesn’t include native code, such as our playback or recording stacks.

We’re not the first to run into Android’s limits in terms of build tools. An internal limitation of Dalvik’s byte code format (DEX), which I will explain in more detail, can leave you unable to build after your codebase reaches a certain size. If you fail to anticipate this, it might happen during the most inconvenient time, such as when you are preparing for a release. Part of our job in Core Engineering at SoundCloud is to make sure our developers are happy and productive; not being able to build our app anymore makes for neither happy nor productive developers.

While there are a number of posts on this topic, I would like to describe in more detail what we have done to combat Android’s method limit, what things worked well and what didn’t work so well, what it actually means to use the dx tool’s --multi-dex switch and what you can do to improve application health with regards to size.

• iOS
• Mobile

When we rebuilt our iOS app, the player was the core focus. The interactive waveform was at the center of the design. It was important both that the player be fast and look good.

Initial implementation

We iterated on the waveform view until it was as responsive as possible. The initial implementation focused on replicating the design, which heavily used CoreGraphics. A single custom view calculates the current bar offset based on its time property. It then draws each of the waveform samples that are in the current visible section of the waveform. Each sample is either rendered as a filled rectangle for unplayed samples, or by adding clip paths to the context then drawing a linear CGGradient…

• iOS
• Mobile

Recently, SoundCloud launched the new iOS application which was a complete rewrite of the existing iOS application. The Mobile engineering team saw this as an opportunity to build a solid foundation for the future of SoundCloud on iOS and to experiment with new technologies and processes at the same time.

In the world of mobile, you deal with data, errors, threads and concurrency a lot. The common scenario starts with a user tapping on the screen. The application jumps off of the main UI thread…

• iOS
• Mobile
• Open Source
• Ruby

I’m excited to announce that SoundCloud is sponsoring the development of CocoaPods through a Travis Foundation grant. CocoaPods is an open-source dependency manager for Objective-C projects. Travis Foundation is a non-profit that pairs corporate sponsors with open-source projects to make open source even better.

At SoundCloud, our iOS team uses CocoaPods every day to manage the dependencies of our mobile apps. We hope that this sponsorship will lead to improvements that benefit the entire Mac…

• Android
• Mobile

A common problem in Android development is that you need to jump off the main UI thread to retrieve data from an IO-based source. At SoundCloud, we use Netflix’s RxJava to simplify asynchronous flows in Android. In an interview given for the Google Developers series “root access Berlin”,  Mustafa Sezgin—who heads up our Mobile Team—explains why we chose RxJava, what it gives us, and he walks through an example-usage pattern:

If you are interested in more details, be sure to catch Matthias Käppler—from our Android Team—give an in-depth talk at Droidcon London…