使用Swift中的AudioToolbox访问OS X主卷 [英] Using AudioToolbox from Swift to access OS X master volume

问题描述

是否可以从我的Swift应用程序中设置系统的主音量?

我阅读了很多有关AudioToolbox的内容，并阅读了Objective-C中的一些源示例.例如，我发现了这一点: 在10.6之后以编程方式设置Mac OS X卷

但是我无法在Swift中运行它.

我在解决方案

(为Swift 4及更高版本更新了代码，可在编辑历史记录中找到Swift 2和3版本.)

这就是我将答案翻译成 更改OS X系统的结果以编程方式 和 设置Mac OS X 10.6(Snow Leopard) 之后以编程方式将音量调至Swift(为简便起见，省略了错误检查):

必需的框架:

import AudioToolbox

获取默认输出设备:

var defaultOutputDeviceID = AudioDeviceID(0)
var defaultOutputDeviceIDSize = UInt32(MemoryLayout.size(ofValue: defaultOutputDeviceID))

var getDefaultOutputDevicePropertyAddress = AudioObjectPropertyAddress(
    mSelector: kAudioHardwarePropertyDefaultOutputDevice,
    mScope: kAudioObjectPropertyScopeGlobal,
    mElement: AudioObjectPropertyElement(kAudioObjectPropertyElementMaster))

let status1 = AudioObjectGetPropertyData(
    AudioObjectID(kAudioObjectSystemObject),
    &getDefaultOutputDevicePropertyAddress,
    0,
    nil,
    &defaultOutputDeviceIDSize,
    &defaultOutputDeviceID)

设置音量:

var volume = Float32(0.50) // 0.0 ... 1.0
var volumeSize = UInt32(MemoryLayout.size(ofValue: volume))

var volumePropertyAddress = AudioObjectPropertyAddress(
    mSelector: kAudioHardwareServiceDeviceProperty_VirtualMasterVolume,
    mScope: kAudioDevicePropertyScopeOutput,
    mElement: kAudioObjectPropertyElementMaster)

let status2 = AudioObjectSetPropertyData(
    defaultOutputDeviceID,
    &volumePropertyAddress,
    0,
    nil,
    volumeSize,
    &volume)

最后，为了完整起见，请获取音量:

var volume = Float32(0.0)
var volumeSize = UInt32(MemoryLayout.size(ofValue: volume))

var volumePropertyAddress = AudioObjectPropertyAddress(
    mSelector: kAudioHardwareServiceDeviceProperty_VirtualMasterVolume,
    mScope: kAudioDevicePropertyScopeOutput,
    mElement: kAudioObjectPropertyElementMaster)

let status3 = AudioObjectGetPropertyData(
    defaultOutputDeviceID,
    &volumePropertyAddress,
    0,
    nil,
    &volumeSize,
    &volume)

print(volume)

为简洁起见，已省略了错误检查.当然，应该在实际应用程序中检查状态返回值是否成功.

信用转到 noamtm 在评论中提到，通过传递

mSelector: kAudioHardwareServiceDeviceProperty_VirtualMasterBalance

到AudioObjectPropertyAddress().

Is there a solution to setting the system's master volume from within my Swift app?

I read a lot about AudioToolbox and read some source examples in Objective-C. For example, I found this: Setting Mac OS X Volume Programatically after 10.6

But I can't get it working in Swift.

I am missing some example code in https://developer.apple.com/library/mac/documentation/AudioToolbox/Reference/AudioHardwareServicesReference/index.html#//apple_ref/c/func/AudioHardwareServiceGetPropertyData

解决方案

(Code updated for Swift 4 and later, the Swift 2 and 3 versions can be found in the edit history.)

This is what I got from translating the answers to Change OS X system volume programmatically and Setting Mac OS X volume programmatically after 10.6 (Snow Leopard) to Swift (error checking omitted for brevity):

Required framework:

import AudioToolbox

Get default output device:

var defaultOutputDeviceID = AudioDeviceID(0)
var defaultOutputDeviceIDSize = UInt32(MemoryLayout.size(ofValue: defaultOutputDeviceID))

var getDefaultOutputDevicePropertyAddress = AudioObjectPropertyAddress(
    mSelector: kAudioHardwarePropertyDefaultOutputDevice,
    mScope: kAudioObjectPropertyScopeGlobal,
    mElement: AudioObjectPropertyElement(kAudioObjectPropertyElementMaster))

let status1 = AudioObjectGetPropertyData(
    AudioObjectID(kAudioObjectSystemObject),
    &getDefaultOutputDevicePropertyAddress,
    0,
    nil,
    &defaultOutputDeviceIDSize,
    &defaultOutputDeviceID)

Set volume:

var volume = Float32(0.50) // 0.0 ... 1.0
var volumeSize = UInt32(MemoryLayout.size(ofValue: volume))

var volumePropertyAddress = AudioObjectPropertyAddress(
    mSelector: kAudioHardwareServiceDeviceProperty_VirtualMasterVolume,
    mScope: kAudioDevicePropertyScopeOutput,
    mElement: kAudioObjectPropertyElementMaster)

let status2 = AudioObjectSetPropertyData(
    defaultOutputDeviceID,
    &volumePropertyAddress,
    0,
    nil,
    volumeSize,
    &volume)

Finally, for the sake of completeness, get the volume:

var volume = Float32(0.0)
var volumeSize = UInt32(MemoryLayout.size(ofValue: volume))

var volumePropertyAddress = AudioObjectPropertyAddress(
    mSelector: kAudioHardwareServiceDeviceProperty_VirtualMasterVolume,
    mScope: kAudioDevicePropertyScopeOutput,
    mElement: kAudioObjectPropertyElementMaster)

let status3 = AudioObjectGetPropertyData(
    defaultOutputDeviceID,
    &volumePropertyAddress,
    0,
    nil,
    &volumeSize,
    &volume)

print(volume)

Error checking has been omitted for brevity. Of course one should check the status return values for success or failure in a real application.

Credits go to Set OS X volume in OS X 10.11 using Swift without using the deprecated AudioHardwareServiceSetPropertyData API for using AudioObjectSetPropertyData() instead of the deprecated AudioHardwareServiceSetPropertyData().

As noamtm mentions in the comments, this works also for getting and setting the left-right balance, by passing

mSelector: kAudioHardwareServiceDeviceProperty_VirtualMasterBalance

to AudioObjectPropertyAddress().

这篇关于使用Swift中的AudioToolbox访问OS X主卷的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！