Using AudioToolbox from Swift to access the bulk of OS X
Is there a solution to set master system volume from my Swift app?
I have read a lot about AudioToolbox and read some source code examples in Objective-C. For example, I found this: Adjusting Mac OS X Volume After 10.6
But I cannot get it to work in Swift.
I am missing the code example at https://developer.apple.com/library/mac/documentation/AudioToolbox/Reference/AudioHardwareServicesReference/index.html#//apple_ref/c/func/AudioHardwareServiceGetPropertyData
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(Code updated for Swift 4 and later, Swift 2 and 3 versions can be found in the edit history.)
Here's what I got by translating the answers to the system volume "Change OS X" programmatically and programmatically setting the Mac OS X volume after 10.6 (Snow Leopard) to "Swift" (brevity check not included):
Mandatory 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, we 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, in a real application, you should check the status return values for success or failure.
Credits go to OS X volume setup on OS X 10.11 using Swift without using the deprecated AudioHardwareServiceSetPropertyData API to use AudioObjectSetPropertyData()
instead of the deprecated one AudioHardwareServiceSetPropertyData()
.
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