SimplyCoreAudio Documentation

To integrate SimplyCoreAudio into your macOS project, use Swift Package Manager (SPM):

1. Add https://github.com/rnine/SimplyCoreAudio.git as a dependency in Xcode.
2. Use the default package options when prompted.
3. Add the SimplyCoreAudio package to your specific target(s).

Requirements:

• Xcode 12+
• Swift 4.0+
• macOS 10.12+

To run tests for SimplyCoreAudio, you must install the NullAudio.driver plugin:

1. Download and build NullAudio.driver (refer to Apple's documentation on creating an audio server driver plug-in).
2. Install it into the system HAL Plug-Ins folder: /Library/Audio/Plug-Ins/HAL.
3. Reload coreaudiod to apply changes.

# Install to HAL folder
# (Move your built driver here)

# Reload coreaudiod
sudo launchctl kill KILL system/com.apple.audio.coreaudiod

To use the framework, import the module, instantiate the SimplyCoreAudio class, and use its properties to interact with audio hardware. You can query default devices, list all devices, filter by scope (input/output), and modify system defaults like the default output device.

import SimplyCoreAudio

let simplyCA = SimplyCoreAudio()

// Get the default output device
let device = simplyCA.defaultOutputDevice

// Get all output devices
let allOutputs = simplyCA.allOutputDevices

// Filter devices by scope
let inputDevices = simplyCA.allDevices.filter { $0.channels(scope: .output) > 0 }

// Set a device as the system default
device.isDefaultOutputDevice = true

Once you have an AudioDevice instance, you can query various hardware properties including sample rate, volume, and preferred stereo channels.

// Get preferred output channels
if let stereoPair = device.preferredChannelsForStereo(scope: .output) {
    let leftChannel = stereoPair.left
    let rightChannel = stereoPair.right
}

// Get device samplerate
if let sampleRate = device.nominalSampleRate {
    // Use samplerate...
}

// Get device virtual main volume
if let outVolume = device.virtualMainVolume(scope: .output) {
    // Use output volume...
}

You can observe system-wide audio changes using NotificationCenter. Common hardware notifications include changes to default devices and the device list.

// Subscribing to `deviceListChanged` notification.
var observer = NotificationCenter.default.addObserver(forName: .deviceListChanged,
                                                       object: nil,
                                                       queue: .main) { (notification) in
    // Get added devices.
    guard let addedDevices = notification.userInfo?["addedDevices"] as? [AudioDevice] else { return }

    // Get removed devices.
    guard let removedDevices = notification.userInfo?["removedDevices"] as? [AudioDevice] else { return }
}

// Cleanup
NotificationCenter.default.removeObserver(observer)
observer = nil

These notifications are sent when properties of a specific AudioStream change.

| Name | Purpose | User Info |
|:---|:---|:---|
| `streamIsActiveDidChange` | Called whenever the audio stream `isActive` flag changes state. | N/A |
| `streamPhysicalFormatDidChange` | Called whenever the audio stream physical format changes. | N/A |

These notifications are broadcast globally when the system audio state changes.

| Name | Purpose | User Info |
|:---|:---|:---|
| `defaultInputDeviceChanged` | Called whenever the default input device changes. | N/A |
| `defaultOutputDeviceChanged` | Called whenever the default output device changes. | N/A |
| `defaultSystemOutputDeviceChanged` | Called whenever the default system output device changes. | N/A |
| `deviceListChanged` | Called whenever the list of hardware devices and device subdevices changes. | `addedDevices: [AudioDevice]`, `removedDevices: [AudioDevice]` |