STM32 microcontrollers are affordable and yet powerful. However, developing software for them with an IDE, such as Keil, is the most painful experience from the perspective of a weekend embedded hobbyist. As such, I decided to seek a way to develop STM32 apps with modern and free tools.
Apple Media Service (AMS) provides a wireless interface for peripherals to control iOS devices’ media player. It is based on the Bluetooth Low Energy (BLE) protocol, which is supported by Zephyr RTOS and many embedded systems. If you want to learn more about BLE, adafruit has a great Introduction to Bluetooth Low Energy article.