Question

I successfully played an mp3 file within the body of a class. However, when I move the functionality out to a separate class, it fails.

Here’s the working code:

Header:

#import <AVFoundation/AVFoundation.h>

@interface QuestionController : UIViewController 
<UITableViewDataSource, UITableViewDelegate, UISplitViewControllerDelegate>
{
    AVAudioPlayer *audioPlayer;

}

working code:

NSURL *url = [NSURL fileURLWithPath:[NSString stringWithFormat:@"%@/A.mp3", [[NSBundle mainBundle] resourcePath]]];

    NSError *error;
    audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:&error];
    audioPlayer.numberOfLoops = 0;

    if (audioPlayer == nil)
        NSLog(@"audio errror: %@",[error description]);             
    else 
        [audioPlayer play];

Here’s the new class:

Header:

#import <Foundation/Foundation.h>
#import <AVFoundation/AVFoundation.h>


    @interface AudioPlayer : NSObject {

    }

    - (void *) playAudioFile:(NSString *) mp3File;

    @end

implementation:

  #import "AudioPlayer.h"

    @implementation AudioPlayer

    - (void *) playAudioFile:(NSString *) mp3File {

        NSLog(@"mp3file to play: %@", mp3File ); 

        NSURL *url = [NSURL fileURLWithPath:[NSString stringWithFormat:@"%@", mp3File, [[NSBundle mainBundle] resourcePath]]];

        NSError *error;

        AVAudioPlayer *audioPlayer;
        audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:&error];
        audioPlayer.numberOfLoops = 0;

        if (audioPlayer == nil) {
            NSLog(@"audio errror: %@",[error description]);
        }
        else {
            [audioPlayer play];
        }
        [audioPlayer release];

        return 0; 
    }   

    @end

Here’s the calling code:

   AudioPlayer *audioPlayer = [[AudioPlayer alloc] init];

   [audioPlayer playAudioFile:@"/A.mp3"];

However, when it runs in the separate class, it doesn’t successfully create the player and goes to the “audio player == nil” branch

Here’s the output:

012-07-21 07:14:54.480 MyQuiz[6655:207] mp3file to play: /A.mp3
2012-07-21 07:15:40.827 MyQuiz[6655:207] audio errror: Error Domain=NSOSStatusErrorDomain Code=-43 "The operation couldn’t be completed. (OSStatus error -43.)"

The url is “file://localhost/A.mp3”

Any ideas what I’m doing wrong? I somehow have always have trouble when I’m refactoring to separate methods. It’s frustrating.

Answer 1

you have an error in the URL, change this line

NSURL *url = [NSURL fileURLWithPath:[NSString stringWithFormat:@"%@", mp3File, [[NSBundle mainBundle] resourcePath]]];

to this:

NSURL *url = [NSURL fileURLWithPath:[NSString stringWithFormat:@"%@%@", [[NSBundle mainBundle] resourcePath], mp3File]];