Playing Sounds/Audio – Audio Session Services

If you need to play short sounds, less than 30 seconds, Audio Session Services are your friend. Here is a snippet of code to play a wav file:

SystemSoundID soundID;
NSString *path = [[NSBundle mainBundle]
   pathForResource:@"RapidFire" ofType:@"wav"];    
 
AudioServicesCreateSystemSoundID((CFURLRef)[NSURL fileURLWithPath:path],&soundID);
AudioServicesPlaySystemSound (soundID);

For this to work, you will need to import <AudioToolbox/AudioToolbox.h> header file, and also add the AudioToolbox.framework to your project.

For those interested in a little background information, Audio Session Services is a set of functions written in C. There are a few subtleties that give this away. Here is the definition for the AudioServicesCreateSystemSoundID function:

OSStatus AudioServicesCreateSystemSoundID (
   CFURLRef       inFileURL, 
   SystemSoundID  *outSystemSoundID);
);

The giveaway is how we call this function:

AudioServicesCreateSystemSoundID((CFURLRef)[NSURL fileURLWithPath:path],&soundID);

Notice the parameter outSystemSoundID, which is a pointer to SystemSoundID, a 32 bit unsigned integer. To pass this value as a pointer in C, you pass the address of the variable, which is done using &soundID.

More tips on Audio Session Services in the works…