Harmony Playground lifts musical experiences to a new level by making full use of the power of spatial audio. Users perceive sound in a three-dimensional environment, giving music an entirely new depth and dynamism. The app was built from the ground up in Swift, to make the most of what iOS devices can do.

The application offers an intuitive interface that lets musicians arrange and edit their tracks directly in a 3D audio environment. For listeners, Harmony Playground offers an immersive way to discover music, where the spatial position of instruments and sounds creates the impression of a live experience – wherever you happen to be.

Spatial audio is transforming the way we experience music, by positioning sound sources in three-dimensional space. For musicians it means they can extend their creativity and build soundscapes that were not possible before. Harmony Playground uses this technology to give artists a platform on which to experiment and innovate. Choosing Swift was deliberate: its close integration with the iOS ecosystem let us take advantage of modern APIs such as Core Audio and AVFoundation to guarantee outstanding audio quality and performance.

Beyond the app itself, Harmony Playground is also committed to the music community: proceeds go towards supporting musical projects and young talent, as set out on the Trust website. The app therefore stands not only for technical innovation, but for social responsibility as well.

The development of Harmony Playground reflects our expertise in iOS development, and in Swift in particular. From the first line of code, the app was built with performance and seamless integration into the Apple ecosystem in mind. Swift was the optimal choice for a safe, performant and maintainable codebase. With SwiftUI we created a modern, reactive interface that is not only visually convincing but also intuitive to use.

On the spatial audio side we worked intensively with Core Audio and Apple's Spatial Audio API to create an immersive 3D sound experience. That covers the precise positioning of sound sources in space, adaptation to head movement through dynamic head tracking, and the use of the latest audio formats such as Dolby Atmos. To keep audio performance at the highest level, we relied on AVAudioEngine and heavily optimised audio pipelines.

On top of that, the app was combined with Metal for striking visualisations that support the 3D audio effect graphically and round out the immersive experience. Our extensive experience with iOS APIs allowed a seamless integration of features such as AirPods Pro support, real-time audio adjustment and adaptive sound settings for different listeners.

The whole architecture was designed for scalability and flexibility. We created a modular codebase that makes it quick to implement new features such as personalised audio adjustment or AI-assisted audio effects. Automated tests with XCTest and UI tests with XCUITest ensured the stability of the app.

With Harmony Playground we showed that we command the full breadth of iOS technologies – from advanced audio processing through to modern Swift frameworks. Our aim was to build an app that is not only innovative, but performant, stable and ready for the future.