Xcode stops on prepareToPlay

Question

Using AVAudioPlayer to add sound to a working application, it stops / hangs on prepareToPlay. Note it also stops / hangs on play. Hitting "Continue program execution" several times makes the application resume. This problem only occurs when running the program in the simulator.

Using Xcode 4.6

Code Snippets:

ViewController.h

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

@interface ViewController : UIViewController <AVAudioPlayerDelegate>

@end

ViewController.m

#import "ViewController.h"

@interface ViewController ()
{
}

@property (nonatomic, strong) AVAudioPlayer *audioPlayer;

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self initilizeAudio];
}

- (void)initilizeAudio
{
    NSError *error = nil;
    NSURL *audioURL = [[NSBundle mainBundle] URLForResource:@"Background" withExtension:@"mp3"];

    self.audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:audioURL error:&error];
    if (error)
    {
        NSLog(@"Error in audioPlayer: %@", [error localizedDescription]);
    }
    else
    {
        [self.audioPlayer setDelegate:self];
        [self.audioPlayer prepareToPlay];
    }
}

@end

Stack trace

0 __cxa_throw
21 -[AVAudioPlayer prepareToPlay]
22 -[ViewController viewDidLoad]
.
.
.

Apparently I am not allowed to answer my own questions yet. so providing the answer in a comment. The problem was I normally develop with a breakpoint set to "All Exceptions", and the actual exception thrown was __cxa_throw. Which apparently turns out to be in C++ libraries that are used to implement AVAudioPlayer. By changing the breakpoint to "All Objective-C Exceptions" the program ran fine. (This can be done by editing the breakpoint and changing the Exception field to Objective-C.) — zermat, Mar 13 '13 at 21:44
According to [This post on Meta](http://meta.stackexchange.com/a/17467) you have to wait for 8 hours if you have less then 100 rep. You can accept your own answer 48 hours later. — Sebastian, Mar 13 '13 at 22:03

score 67 · Accepted Answer · edited Aug 05 '13 at 00:34

67

The problem was I normally develop with a breakpoint set to "All Exceptions", and the actual exception thrown was __cxa_throw. Which apparently turns out to be in C++ libraries that are used to implement AVAudioPlayer. By changing the breakpoint to "All Objective-C Exceptions" the program ran fine. (This can be done by editing the breakpoint and changing the Exception field to Objective-C.

edited Aug 05 '13 at 00:34

Sebastian

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answered Mar 14 '13 at 07:27

zermat

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1

Awesome, I am glad you posted this because I was scratching my head on this one!!! – LilMoke Mar 26 '13 at 08:55
1

You sir, saved my day! I can't thank you enough! I had the exact same problem and it was driving me nuts. :-) – thomas May 01 '13 at 06:35
Thank you! I was starting to scratch my head since it suddenly stopped working without any changes in my code. It appears that I too had activated an "all exceptions" breakpoint.... – Erwan Feb 04 '14 at 03:23
Nice one!! I've been scratching my head at this for the last two years -- prepareToPlay and play always crash in newer iOS versions on the simulator. Changed the exception breaks as you suggested...problem solved. Thanks a million! – Mike Critchley Apr 09 '18 at 23:24

score 4 · Answer 2 · edited May 23 '17 at 12:09

I had this problem too. The solution above works, but I think there's a better way to fix it.

The errors the author suggests ignoring are indicating that the mac is trying to send audio to a device that isn't working. I'm guessing the code is written in C, so turning the exceptions to "objective-c only" does silence the exception.

The real fix is to get the audio device working again. For me, the reason for the failure was that I was switching around some audio input and output, but (it seems) IOS simulator had remembered the old settings. So when I tried the various steps in this thread:

Error '!dat' trying to set the (null) audio devices' sample rate

I got the audio to work again, and it stopped throwing any exceptions.

Isn't the problem rather that there is no audio hardware on the simulator and that this seems to cause an intermediate C++ exception which can (should) be ignored (my mechanism suggested in accepted answer). — Drux, Feb 25 '15 at 10:49

Xcode stops on prepareToPlay

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