xcode: How to save audio file after recording audio using AVFoundation

问题

I browsed through all kinds of post related to this topic but the answers just do not really help. I used this tutorial to implement recording of audio files and playback. What seems to be missing is how to save the record permanently. When I exit my app the sound file is there but nothing is in it. I don't even know if it is saving the rocerd or just creating the file. Here is a code sample:

NSArray *dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docsDir = [dirPaths objectAtIndex:0];
NSString *soundFilePath = [docsDir
                               stringByAppendingPathComponent:@"tmpSound.caf"];

tempRecFile = [NSURL fileURLWithPath:soundFilePath];

NSDictionary *recSettings = [NSDictionary 
                                    dictionaryWithObjectsAndKeys:
                                    [NSNumber numberWithInt:AVAudioQualityMin],
                                    AVEncoderAudioQualityKey,
                                    [NSNumber numberWithInt:16], 
                                    AVEncoderBitRateKey,
                                    [NSNumber numberWithInt: 2], 
                                    AVNumberOfChannelsKey,
                                    [NSNumber numberWithFloat:44100.0], 
                                    AVSampleRateKey,
                                    nil];

recorder = [[AVAudioRecorder alloc] initWithURL:tempRecFile settings:recSettings error:nil];
[recorder setDelegate:self];
[recorder prepareToRecord];
[recorder record];

I saw a possible solution to this problem here but since I'm new to iOS I do not really get it or it is just does not working for me.

Please help and provide a code example. I read the documentation about AVFoundation and other classes but with no positive results.

SOS :)

UPDATE This is my recording method:

-(IBAction)recording{
    //***** METHOD for recording

    if(isNotRecording){
        isNotRecording = NO;
        [recButton setTitle:@"Stop"  forState:UIControlStateNormal];
        recStateLabel.text = @"Recording";

        [recorder setDelegate:self];
        [recorder prepareToRecord];
        [recorder record];

    }
    else{
        isNotRecording = YES;
        [recButton setTitle:@"Rec Begin" forState:UIControlStateNormal];
        playButton.hidden = NO;
        recStateLabel.text = @"Not recording";
        [recorder stop];
    }


}

This is my viewDidLoad:

- (void)viewDidLoad
{
    //record sound test code - start
    isNotRecording = YES;
    //playButton.hidden = YES;
    recStateLabel.text = @"Not recording";

    AVAudioSession *audioSession = [AVAudioSession sharedInstance];

    [audioSession setCategory:AVAudioSessionCategoryPlayAndRecord error:nil];

    [audioSession setActive:YES error:nil];
    //record sound test code -  END

    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.

    // code for generating the sound file that is to be saved
    NSArray *dirPaths;
    NSString *docsDir;

    dirPaths = NSSearchPathForDirectoriesInDomains(
                                                   NSDocumentDirectory, NSUserDomainMask, YES);
    docsDir = [dirPaths objectAtIndex:0];
    NSString *soundFilePath = [docsDir
                               stringByAppendingPathComponent:@"sound.caf"];

    NSURL *soundFileURL = [NSURL fileURLWithPath:soundFilePath];

    NSDictionary *recordSettings = [NSDictionary 
                                    dictionaryWithObjectsAndKeys:
                                    [NSNumber numberWithInt:AVAudioQualityMin],
                                    AVEncoderAudioQualityKey,
                                    [NSNumber numberWithInt:16], 
                                    AVEncoderBitRateKey,
                                    [NSNumber numberWithInt: 2], 
                                    AVNumberOfChannelsKey,
                                    [NSNumber numberWithFloat:44100.0], 
                                    AVSampleRateKey,
                                    nil];

    NSError *error = nil;

    recorder = [[AVAudioRecorder alloc]
                     initWithURL:soundFileURL
                     settings:recordSettings
                     error:&error];

    if (error)
    {
        NSLog(@"error: %@", [error localizedDescription]);

    } else {
        [recorder prepareToRecord];
    }

}

This is my playBack method:

-(IBAction)playback{
    //AVAudioPlayer *player = [[AVAudioPlayer alloc] initWithContentsOfURL:temporaryRecFile error:nil];
    NSError *error;
    // setting the uri of the formed created file
    NSArray *dirPaths;
    NSString *docsDir;



dirPaths = NSSearchPathForDirectoriesInDomains(
                                               NSDocumentDirectory, NSUserDomainMask, YES);
docsDir = [dirPaths objectAtIndex:0];
NSString *soundFilePath = [docsDir
                           stringByAppendingPathComponent:@"sound.caf"];

NSURL *soundFileURL = [NSURL fileURLWithPath:soundFilePath];

AVAudioPlayer *player = [[AVAudioPlayer alloc]initWithContentsOfURL:soundFileURL error:&error];



[player setNumberOfLoops:0];
[player prepareToPlay];
[player setVolume:1];
[player play];
NSLog(@"URL je: %@", soundFileURL);


//method 2
if (error)
    NSLog(@"Error: %@", 
          [error localizedDescription]);
else
{

    [player play];
    if(player.isPlaying==YES)
    {
        NSLog(@"It's playing");
    }
}

}

I hopše this makes it clear what I do. Any suggestions where I might be wrong?

回答1:

You need to stop recording in order to save the data to the file permanently:

[recorder stop];

回答2:

The problem is that when you tell XCode (in the viewDidLoad method) to [recorder prepareToRecord]; it gets rid of the previously recorded audio file. Eliminate that piece of code in the "if" statement and your audio file WILL be saved when you exit and come back in to the app.

回答3:

FYI -- The "[recorder prepareToRecord]" method creates a fresh audio file, overwriting any previous recorded file.

来源：https://stackoverflow.com/questions/9387237/xcode-how-to-save-audio-file-after-recording-audio-using-avfoundation