How do I turn my iPhone into a strobe light?

How Do Things Work on Instagram: "Strobe lights that move perfectly with the beat rely on a combination of audio analysis and digital control systems. At the core is an audio input—either from a microphone or a direct feed from the sound system—which captures the music in real time. This signal is then processed by software or a controller that breaks the sound into components like bass, mids, and treble. Since beats usually sit in the low-frequency (bass) range, the system detects these peaks a