Strange Issue loading audio files within app - ios

Question

I am having issues loading certain audio files in my app, certain songs /audio will work fine, others do not and I can't figure out how or why.
When it is cloud based iTunes music, it does not work for sure, but mostly if the music has been downloaded to the device from iTunes, it will load, but even then, some files simply refuse to load.
Here is the code, for opening;
#define EXPORT_NAME #"exported.m4a"
- (void) openSoundFile:(ProductInfo*)info
{
[self dismissViewControllerAnimated:YES completion:nil];
if (currentProduct) {
[currentProduct release];
currentProduct = nil;
}
currentProduct = [[ProductInfo alloc] init];
currentProduct.index = info.index;
currentProduct.parent = info.parent;
currentProduct.title = [info.title copy];
currentProduct.name = [info.name copy];
currentProduct.tempo = info.tempo;
currentProduct.pitch = info.pitch;
currentProduct.key = info.key;
[m_lblName setText:info.title];
[m_viewIsLoading setHidden:NO];
[self loadSoundFileToM4A];
}
Then we show loadSoundFileToM4A method;
-(void) loadSoundFileToM4A
{
NSURL *assetURL = [NSURL URLWithString:currentProduct.name];
AVURLAsset *songAsset = [AVURLAsset URLAssetWithURL:assetURL options:nil];
AVAssetExportSession *exporter = [[AVAssetExportSession alloc]
initWithAsset: songAsset
presetName: AVAssetExportPresetAppleM4A];
exporter.outputFileType = #"com.apple.m4a-audio";
// set up export (hang on to exportURL so convert to PCM can find it)
NSArray *dirs = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectoryPath = [dirs objectAtIndex:0];
NSString *exportPath = [[documentsDirectoryPath stringByAppendingPathComponent:EXPORT_NAME] retain];
if ([[NSFileManager defaultManager] fileExistsAtPath:exportPath]) {
[[NSFileManager defaultManager] removeItemAtPath:exportPath error:nil];
}
NSURL *exportURL = [NSURL fileURLWithPath:exportPath];
exporter.outputURL = exportURL;
// do the export
[exporter exportAsynchronouslyWithCompletionHandler:^{
int exportStatus = exporter.status;
switch (exportStatus) {
case AVAssetExportSessionStatusFailed: {
// log error to text view
NSError *exportError = exporter.error;
NSLog (#"AVAssetExportSessionStatusFailed: %#", exportError);
[self loadSoundFileFail];
break;
}
case AVAssetExportSessionStatusCompleted: {
NSLog (#"AVAssetExportSessionStatusCompleted");
// set up AVPlayer
[self loadSoundFile];
break;
}
case AVAssetExportSessionStatusUnknown: { NSLog (#"AVAssetExportSessionStatusUnknown"); break;}
case AVAssetExportSessionStatusExporting: { NSLog (#"AVAssetExportSessionStatusExporting"); break;}
case AVAssetExportSessionStatusCancelled: { NSLog (#"AVAssetExportSessionStatusCancelled"); break;}
case AVAssetExportSessionStatusWaiting: { NSLog (#"AVAssetExportSessionStatusWaiting"); break;}
default: { NSLog (#"didn't get export status"); break;}
}
}];
}
when it fails, it uses this method;
- (void) loadSoundFileFail
{
[m_viewIsLoading setHidden:YES];
UIAlertView* alert = [[UIAlertView alloc] initWithTitle:#"Failed"
message:#"Couldn't load file"
delegate:self
cancelButtonTitle:nil
otherButtonTitles:#"OK", nil];
[alert show];
}
And on success, this is the method;
- (void) loadSoundFile
{
[m_viewIsLoading setHidden:YES];
NSArray *dirs = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectoryPath = [dirs objectAtIndex:0];
NSString *exportPath = [[documentsDirectoryPath stringByAppendingPathComponent:EXPORT_NAME] retain];
if ([[NSFileManager defaultManager] fileExistsAtPath:exportPath]) {
if( m_pPlayer != NULL )
{
if( m_pPlayer->IsRunning() )
{
OSStatus result = m_pPlayer->StopQueue();
if (result == noErr)
[[NSNotificationCenter defaultCenter] postNotificationName:#"soundQueueResumed" object:self];
}
m_pPlayer->DisposeQueue( TRUE );
CFStringRef strFilePath = (CFStringRef)exportPath;
m_pPlayer->CreateQueueForFile( strFilePath );
nTempo = (float)currentProduct.tempo;
nPitch = (float)currentProduct.pitch/100.0f;
nKey = (float)currentProduct.key;
[self setKeyValue];
[self setTempoValue];
[self setPitchValue];
[m_sldTempo setValue:nTempo];
[m_sldPitch setValue:nPitch];
[m_sldKey setValue:nKey];
[self setRepeatSwitchState];
[self setReverseSwitchState];
// Set the button's state back to "record"
if( m_pPlayer->Queue() == NULL )
m_btnPlay.enabled = NO;
else
m_btnPlay.enabled = YES;
}
}
}
I capture this error in the debugger;
AVAssetExportSessionStatusFailed: Error Domain=NSURLErrorDomain Code=-1 "unknown error"
UserInfo=0x1700ffa80 {NSUnderlyingError=0x17804edf0 "The operation couldn’t be completed.
(OSStatus error -12935.)", NSErrorFailingURLStringKey=(null), NSErrorFailingURLKey=(null), NSURL=(null),
NSLocalizedDescription=unknown error}