iPhone SDK: Cross fade Sound using Core Audio-AVAudioPlayer

The Problem: Had 4 audio files that needed to be played depending on the stage the user was in the App. During the transition from one audio files to another, the sound needs to crossfade.

The solution:

1. For simplicity created 4 AVAudioPlayer class members as such: (can be done with 2 but the logic gets more complicated)

[code]

#import "MyPlayer.h"

#import <AVFoundation/AVFoundation.h>

@interface ImageExampleViewController : UIViewController {

MyPlayer *audioPlayerForest;

MyPlayer *audioPlayerForestCalm;

MyPlayer *audioPlayerCamp;

MyPlayer *audioPlayerTown;

}

@property(nonatomic , retain)MyPlayer *audioPlayerForest;

@property(nonatomic , retain)MyPlayer *audioPlayerForestCalm;

@property(nonatomic , retain)MyPlayer *audioPlayerCamp;

@property(nonatomic , retain)MyPlayer *audioPlayerTown;

@end

[/code]

2. MyPlayer is a subclass of AVAudioPlayer with one additional property storing the state of the sound:

#import <Foundation/Foundation.h>

#import <AVFoundation/AVFoundation.h>

typedef enum {

starting = 0,

started = 1,

stopping = 2,

stopped = 3

} statePlayer;

@interface MyPlayer : AVAudioPlayer {

statePlayer state ;

}

@property(nonatomic) statePlayer state ;

 

@end

----------------

#import "MyPlayer.h"

@implementation MyPlayer

@synthesize state;

- (id)init

{

self = [super init];

if (self) {

// Initialization code here.

}

return self;

}

@end