FM Playground is an educational app designed for learning and experimenting with FM synthesis (Frequency Modulation Synthesis). Developed as part of the "2025 Swift Sound - Creative Coding for Computer Musicians" project at MARTE Lab, Department of Multimedia, Dongguk University, by Yeonho Kim, Taejun Kim, Seoyul Son, and Sookyung Yoon, with guidance from Gwangyu Lee. The app features multiple interactive views where users can manipulate sound in real time using touch gestures and iPhone sensors (gyroscope, compass, etc.). Key Features: - What is FM Synthesis?: Learn the fundamentals of FM synthesis with an interactive view. Adjust sliders to hear real-time modulation effects and explore complex timbres. - Gesture-based control of timbre, frequency, and volume across various interactive views. - Open-source code available for study, experimentation, and expansion.