Question

i’m new in Objective C, i’m developing an app that play sound on touch event of an uibutton.
When i touch the button, it change is image and audio starts to playing. When audio is finish to play, i want to put the original image of uibutton. How can i do that? How can i catch the event of the audio that is finish?
i’m using that code:

- (SystemSoundID) createSoundID: (NSString*)name
{
    NSString *path = [NSString stringWithFormat: @"%@/%@",
    [[NSBundle mainBundle] resourcePath], name];              
    NSURL* filePath = [NSURL fileURLWithPath: path isDirectory: NO];
    SystemSoundID soundID;
    AudioServicesCreateSystemSoundID((CFURLRef)filePath, &soundID);
    return soundID;
} 

In

viewDidLoad

i call

freq = [self createSoundID: @"freq.wav"];

and in function that is called on button’s touch i use:

AudioServicesPlaySystemSound(freq);

How can i do? Thank you!

Answer 1

Not sure if it’s possible with the AudioService API but you can use AVAudioPlayer instead and assign a delegate that implements the AVAudioPlayerDelegate protocol and does something when audioPlayerDidFinishPlaying:successfully: is called.

Remember to add the AVFoundation framework.

Example:

In your interface definition:

#import <AVFoundation/AVFoundation.h>

…

@inteface SomeViewController : UIViewController <AVAudioPlayerDelegate>

…

@propety(nonatomic, retain) AVAudioPlayer *player;

In your implementation:

@synthesize player;

…

// in some viewDidLoad or init method
self.player = [[[AVAudioPlayer alloc] initWithContentsOfURL:soundUrl error:NULL] autorelease];
self.player.delegate = self;

…

- (void)pressButton:(id)sender {
  // set play image
  [self.player stop];
  self.player.currentTime = 0;
  [self.player play];
}

…

- (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag {
   // set finish image
}

…

# in some dealloc or viewDidUnload method
self.player = nil;