How to turn off bluetooth device and sound device in Cocoa? - objective-c

Question

I've known that Airport can be turned off by CoreWLAN framework.
So, I think there are probably functions or frameworks related with bluetooth device and sound device.
How can I turn off that devices?

Answer 1

I assume you by "cannot have power so that it cannot speak", you mean you simply want to mute the speaker. I found some neat sample code here, using CoreAudio to mute the system's default speaker: http://cocoadev.com/index.pl?SoundVolume
I took the liberty of converting it to pure C and trying it out.
#import <CoreAudio/CoreAudio.h>
#import <stdio.h>
// getting system volume
float getVolume() {
float b_vol;
OSStatus err;
AudioDeviceID device;
UInt32 size;
UInt32 channels[2];
float volume[2];
// get device
size = sizeof device;
err = AudioHardwareGetProperty(kAudioHardwarePropertyDefaultOutputDevice, &size, &device);
if(err!=noErr) {
printf("audio-volume error get device\n");
return 0.0;
}
// try set master volume (channel 0)
size = sizeof b_vol;
err = AudioDeviceGetProperty(device, 0, 0, kAudioDevicePropertyVolumeScalar, &size, &b_vol); //kAudioDevicePropertyVolumeScalarToDecibels
if(noErr==err) return b_vol;
// otherwise, try seperate channels
// get channel numbers
size = sizeof(channels);
err = AudioDeviceGetProperty(device, 0, 0,kAudioDevicePropertyPreferredChannelsForStereo, &size,&channels);
if(err!=noErr) printf("error getting channel-numbers\n");
size = sizeof(float);
err = AudioDeviceGetProperty(device, channels[0], 0, kAudioDevicePropertyVolumeScalar, &size, &volume[0]);
if(noErr!=err) printf("error getting volume of channel %d\n",channels[0]);
err = AudioDeviceGetProperty(device, channels[1], 0, kAudioDevicePropertyVolumeScalar, &size, &volume[1]);
if(noErr!=err) printf("error getting volume of channel %d\n",channels[1]);
b_vol = (volume[0]+volume[1])/2.00;
return b_vol;
}
// setting system volume
void setVolume(float involume) {
OSStatus err;
AudioDeviceID device;
UInt32 size;
Boolean canset = false;
UInt32 channels[2];
//float volume[2];
// get default device
size = sizeof device;
err = AudioHardwareGetProperty(kAudioHardwarePropertyDefaultOutputDevice, &size, &device);
if(err!=noErr) {
printf("audio-volume error get device\n");
return;
}
// try set master-channel (0) volume
size = sizeof canset;
err = AudioDeviceGetPropertyInfo(device, 0, false, kAudioDevicePropertyVolumeScalar, &size, &canset);
if(err==noErr && canset==true) {
size = sizeof involume;
err = AudioDeviceSetProperty(device, NULL, 0, false, kAudioDevicePropertyVolumeScalar, size, &involume);
return;
}
// else, try seperate channes
// get channels
size = sizeof(channels);
err = AudioDeviceGetProperty(device, 0, false, kAudioDevicePropertyPreferredChannelsForStereo, &size,&channels);
if(err!=noErr) {
printf("error getting channel-numbers\n");
return;
}
// set volume
size = sizeof(float);
err = AudioDeviceSetProperty(device, 0, channels[0], false, kAudioDevicePropertyVolumeScalar, size, &involume);
if(noErr!=err) printf("error setting volume of channel %d\n",channels[0]);
err = AudioDeviceSetProperty(device, 0, channels[1], false, kAudioDevicePropertyVolumeScalar, size, &involume);
if(noErr!=err) printf("error setting volume of channel %d\n",channels[1]);
}
int main() {
printf("The system's volume is currently %f\n", getVolume());
printf("Setting volume to 0.\n");
setVolume(0.0f);
return 0;
}
I ran it and got this:
[04:29:03] [william#enterprise ~/Documents/Programming/c]$ gcc -framework CoreAudio -o mute.o coreaudio.c
.. snipped compiler output..
[04:29:26] [william#enterprise ~/Documents/Programming/c]$ ./mute.o
The system's volume is currently 0.436749
Setting volume to 0.
Hopefully this sends you in the right direction.