iOS Microphone

Turn your old iPhone into a wired microphone. Routes audio from the built-in mic to the headphone jack in real-time.

Why?

I wanted to use my old iPhone as a wired microphone for my computers, because the phone had no other use. Useful for streaming, podcasting, or recording without buying a dedicated microphone — especially if you have an older iPhone with a 3.5mm jack lying around.

Features

• One-tap mic passthrough (mic to speaker/headphones)
• Works in the background and with the screen locked
• Minimal latency using AVAudioEngine
• Supports iOS 9.0+

Limitations

• Audio passthrough only — no recording or streaming features
• Tested on iPhone 4s, 5s, 6 / 6s, SE1 / 2, 11 and 15 Pro
• Not tested on iPad

Important Notes

• iPhone 7 and newer require a Lightning-to-3.5mm adapter (or USB-C-to-3.5mm for iPhone 15+), since these models no longer have a built-in headphone jack.
• Always use headphones or a connected output device. Running the app without headphones will cause audio feedback (loud screeching) as the speaker output loops back into the microphone.

Requirements

• iOS 9.0 or later
• A physical iOS device (microphone input is not available in the simulator)
• Xcode 12 for iOS 9 to 14 (legacy UIKit codebase)
• Xcode 26 for iOS 15.6 to 26.4.2 (SwiftUI codebase)

The project contains two separate implementations sharing the same core logic. Use the Xcode version matching your target iOS range.

Setup

1. Clone the repository
2. Open iOS Microphone.xcodeproj in Xcode
3. Select your development team under Signing & Capabilities
4. Build and run on your device

Usage

1. Connect headphones to your iPhone (use a Lightning or USB-C adapter for iPhone 7 and newer)
2. Launch the app and grant microphone permission
3. Tap the microphone button to start audio passthrough
4. Tap again to stop

License

Released under the MIT License. See LICENSE for details.