How do I record audio on iPhone with AVAudioRecorder?

Actually, there are no examples at all. Here is my working code. Recording is triggered by the user pressing a button on the navBar. The recording uses cd quality (44100 samples), stereo (2 channels) linear pcm. Beware: if you want to use a different format, especially an encoded one, make sure you fully understand how to set the AVAudioRecorder settings (read carefully the audio types documentation), otherwise you will never be able to initialize it correctly. One more thing. In the code, I am not showing how to handle metering data, but you can figure it out easily. Finally, note that the AVAudioRecorder method deleteRecording as of this writing crashes your application. This is why I am removing the recorded file through the File Manager. When recording is done, I save the recorded audio as NSData in the currently edited object using KVC.

#define DOCUMENTS_FOLDER [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"]


- (void) startRecording{

UIBarButtonItem *stopButton = [[UIBarButtonItem alloc] initWithTitle:@"Stop" style:UIBarButtonItemStyleBordered  target:self action:@selector(stopRecording)];
self.navigationItem.rightBarButtonItem = stopButton;
[stopButton release];

AVAudioSession *audioSession = [AVAudioSession sharedInstance];
NSError *err = nil;
[audioSession setCategory :AVAudioSessionCategoryPlayAndRecord error:&err];
if(err){
    NSLog(@"audioSession: %@ %d %@", [err domain], [err code], [[err userInfo] description]);
    return;
}
[audioSession setActive:YES error:&err];
err = nil;
if(err){
    NSLog(@"audioSession: %@ %d %@", [err domain], [err code], [[err userInfo] description]);
    return;
}

recordSetting = [[NSMutableDictionary alloc] init];

[recordSetting setValue :[NSNumber numberWithInt:kAudioFormatLinearPCM] forKey:AVFormatIDKey];
[recordSetting setValue:[NSNumber numberWithFloat:44100.0] forKey:AVSampleRateKey]; 
[recordSetting setValue:[NSNumber numberWithInt: 2] forKey:AVNumberOfChannelsKey];

[recordSetting setValue :[NSNumber numberWithInt:16] forKey:AVLinearPCMBitDepthKey];
[recordSetting setValue :[NSNumber numberWithBool:NO] forKey:AVLinearPCMIsBigEndianKey];
[recordSetting setValue :[NSNumber numberWithBool:NO] forKey:AVLinearPCMIsFloatKey];



// Create a new dated file
NSDate *now = [NSDate dateWithTimeIntervalSinceNow:0];
NSString *caldate = [now description];
recorderFilePath = [[NSString stringWithFormat:@"%@/%@.caf", DOCUMENTS_FOLDER, caldate] retain];

NSURL *url = [NSURL fileURLWithPath:recorderFilePath];
err = nil;
recorder = [[ AVAudioRecorder alloc] initWithURL:url settings:recordSetting error:&err];
if(!recorder){
    NSLog(@"recorder: %@ %d %@", [err domain], [err code], [[err userInfo] description]);
    UIAlertView *alert =
    [[UIAlertView alloc] initWithTitle: @"Warning"
                               message: [err localizedDescription]
                              delegate: nil
                     cancelButtonTitle:@"OK"
                     otherButtonTitles:nil];
    [alert show];
    [alert release];
    return;
}

//prepare to record
[recorder setDelegate:self];
[recorder prepareToRecord];
recorder.meteringEnabled = YES;

BOOL audioHWAvailable = audioSession.inputIsAvailable;
if (! audioHWAvailable) {
    UIAlertView *cantRecordAlert =
    [[UIAlertView alloc] initWithTitle: @"Warning"
                               message: @"Audio input hardware not available"
                              delegate: nil
                     cancelButtonTitle:@"OK"
                     otherButtonTitles:nil];
    [cantRecordAlert show];
    [cantRecordAlert release]; 
    return;
}

// start recording
[recorder recordForDuration:(NSTimeInterval) 10];

}

- (void) stopRecording{

[recorder stop];

NSURL *url = [NSURL fileURLWithPath: recorderFilePath];
NSError *err = nil;
NSData *audioData = [NSData dataWithContentsOfFile:[url path] options: 0 error:&err];
if(!audioData)
    NSLog(@"audio data: %@ %d %@", [err domain], [err code], [[err userInfo] description]);
[editedObject setValue:[NSData dataWithContentsOfURL:url] forKey:editedFieldKey];   

//[recorder deleteRecording];


NSFileManager *fm = [NSFileManager defaultManager];

err = nil;
[fm removeItemAtPath:[url path] error:&err];
if(err)
    NSLog(@"File Manager: %@ %d %@", [err domain], [err code], [[err userInfo] description]);



UIBarButtonItem *startButton = [[UIBarButtonItem alloc] initWithTitle:@"Record" style:UIBarButtonItemStyleBordered  target:self action:@selector(startRecording)];
self.navigationItem.rightBarButtonItem = startButton;
[startButton release];

}

- (void)audioRecorderDidFinishRecording:(AVAudioRecorder *) aRecorder successfully:(BOOL)flag
{

NSLog (@"audioRecorderDidFinishRecording:successfully:");
// your actions here

}

I've been trying to get this code to work for the last 2 hours and though it showed no error on the simulator, there was one on the device.

Turns out, at least in my case that the error came from directory used (bundle) :

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

It was not writable or something like this... There was no error except the fact that prepareToRecord failed...

I therefore replaced it by :

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *recDir = [paths objectAtIndex:0];
NSURL *url = [NSURL fileURLWithPath:[NSString stringWithFormat:@"%@/recordTest.caf", recDir]]

It now Works like a Charm.

Hope this helps others.

Ok so the answer I got helped me in the right direction and I am very thankful. It helped me figure out how to actually record on the iPhone, but I thought I would also include some helpful code I got from the iPhone Reference Library:

AudioandVideoTechnologies

I used this code and added it to the avTouch example fairly easily. With the above code sample and the sample from the reference library, I was able to get this to work pretty good.

As per the above answers, I made some changes and I got the correct output.

Step 1: Under "inf.plist" add the Microphone usage permissions ==>

  <key>NSMicrophoneUsageDescription</key>
  <string>${PRODUCT_NAME} Microphone Usage</string>

Step 2:

1. Save record audio file into Local Document Directory

2. Play/Stop recording

3. Get the Duration of Saved audio file

Here is the source code. Please have a look at once and use it.

ViewController.h

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

@interface ViewController : UIViewController{
AVAudioPlayer *audioPlayer;
AVAudioRecorder *audioRecorder;
}

-(IBAction) startRecording;
-(IBAction) stopRecording;
-(IBAction) playRecording;
-(IBAction) stopPlaying;

@end

ViewController.m

#import "ViewController.h"
@interface ViewController () <AVAudioRecorderDelegate, AVAudioPlayerDelegate>

@end

@implementation ViewController

- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}

-(IBAction) startRecording{
// Setup audio session
AVAudioSession *audioSession = [AVAudioSession sharedInstance];
NSError *err = nil;
[audioSession setCategory :AVAudioSessionCategoryPlayAndRecord error:&err];
if(err)
{
    NSLog(@"audioSession: %@ %ld %@", [err domain], (long)[err code], [[err userInfo] description]);
    return;
}
[audioSession setActive:YES error:&err];
err = nil;
if(err)
{
    NSLog(@"audioSession: %@ %ld %@", [err domain], (long)[err code], [[err userInfo] description]);
    return;
}
AVAudioSessionRecordPermission permissionStatus = [audioSession recordPermission];
switch (permissionStatus) {
    case AVAudioSessionRecordPermissionUndetermined:{
        [[AVAudioSession sharedInstance] requestRecordPermission:^(BOOL granted) {
            // CALL YOUR METHOD HERE - as this assumes being called only once from user interacting with permission alert!
            if (granted) {
                // Microphone enabled code
                NSLog(@"Mic permission granted.  Call method for granted stuff.");
                [self startRecordingAudioSound];
            }
            else {
                // Microphone disabled code
                NSLog(@"Mic permission indeterminate. Call method for indeterminate stuff.");
                //        UIApplication.sharedApplication().openURL(NSURL(string: UIApplicationOpenSettingsURLString)!)
            }
        }];
        break;
    }
    case AVAudioSessionRecordPermissionDenied:
        // direct to settings...
        NSLog(@"Mic permission denied. Call method for denied stuff.");

        break;
    case AVAudioSessionRecordPermissionGranted:
        // mic access ok...
        NSLog(@"Mic permission granted.  Call method for granted stuff.");
        [self startRecordingAudioSound];
        break;
    default:
        // this should not happen.. maybe throw an exception.
        break;
}
}

#pragma mark - Audio Recording
- (BOOL)startRecordingAudioSound{
NSError *error = nil;
NSMutableDictionary *recorderSettings = [[NSMutableDictionary alloc] init];
[recorderSettings setValue :[NSNumber numberWithInt:kAudioFormatLinearPCM] forKey:AVFormatIDKey];
[recorderSettings setValue:[NSNumber numberWithFloat:44100.0] forKey:AVSampleRateKey];
[recorderSettings setValue:[NSNumber numberWithInt: 2] forKey:AVNumberOfChannelsKey];
[recorderSettings setValue :[NSNumber numberWithInt:16] forKey:AVLinearPCMBitDepthKey];
[recorderSettings setValue :[NSNumber numberWithBool:NO] forKey:AVLinearPCMIsBigEndianKey];
[recorderSettings setValue :[NSNumber numberWithBool:NO] forKey:AVLinearPCMIsFloatKey];

// Create a new audio file
NSArray *searchPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentPath_ = [searchPaths objectAtIndex: 0];
NSString *pathToSave = [documentPath_ stringByAppendingPathComponent:[self dateString]];
NSLog(@"the path is %@",pathToSave);

// File URL
NSURL *url = [NSURL fileURLWithPath:pathToSave];//FILEPATH];

//Save recording path to preferences
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
[prefs setURL:url forKey:@"Test1"];
[prefs synchronize];

audioRecorder = [[AVAudioRecorder alloc] initWithURL:url settings:recorderSettings error:&error];
if (!audioRecorder)
{
    NSLog(@"Error establishing recorder: %@", error.localizedFailureReason);
    return NO;
}

// Initialize degate, metering, etc.
audioRecorder.delegate = self;
audioRecorder.meteringEnabled = YES;
//self.title = @"0:00";

if (![audioRecorder prepareToRecord])
{
    NSLog(@"Error: Prepare to record failed");
    //[self say:@"Error while preparing recording"];
    return NO;
}

if (![audioRecorder record])
{
    NSLog(@"Error: Record failed");
    //  [self say:@"Error while attempting to record audio"];
    return NO;
}
NSLog(@"Recroding Started");
return YES;
}

#pragma mark - AVAudioRecorderDelegate
- (void) audioRecorderDidFinishRecording:(AVAudioRecorder *)avrecorder successfully:(BOOL)flag{
NSLog (@"audioRecorderDidFinishRecording:successfully:");
}

#pragma mark - AVAudioPlayerDelegate
- (void) audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag{
NSLog (@"audioPlayerDidFinishPlaying:successfully:");
}

- (NSString *) dateString {
// return a formatted string for a file name
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
formatter.dateFormat = @"ddMMMYY_hhmmssa";
return [[formatter stringFromDate:[NSDate date]]stringByAppendingString:@".aif"];
}

-(IBAction) stopRecording{
NSLog(@"stopRecording");
[audioRecorder stop];
NSLog(@"stopped");
}

-(IBAction) playRecording{
//Load recording path from preferences
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
NSURL *temporaryRecFile = [prefs URLForKey:@"Test1"];

//Get Duration of Audio File
AVURLAsset* audioAsset = [AVURLAsset URLAssetWithURL:temporaryRecFile options:nil];
CMTime audioDuration = audioAsset.duration;
float audioDurationSeconds = CMTimeGetSeconds(audioDuration);
NSLog(@"Duration Of Audio: %f", audioDurationSeconds);

audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:temporaryRecFile error:nil];
audioPlayer.delegate = self;
[audioPlayer setNumberOfLoops:0];
audioPlayer.volume = 1;
[audioPlayer prepareToPlay];
[audioPlayer play];
NSLog(@"playing");
}

-(IBAction) stopPlaying{
NSLog(@"stopPlaying");
[audioPlayer stop];
NSLog(@"stopped");
 }

 @end

These answers are all in Objective-C, here is an answer in Swift. The only thing not included here are the pList Microphone Permissions that are necessary to allow recording.

The steps are laid out in 17 comments

class ViewController: UIViewController {    

    var arrOfRecordingUrls: [URL]() // 0. this is for the recordings once you stop recording in step 15. What you do with the recordings afterwards is up to to you.

    var micRecorder: AVAudioRecorder? // 1. AVAudioRecorder instance that you will initialize every time you start to record in step 6
    
    override func viewDidLoad() {
        super.viewDidLoad()

        // 2. set the AudioSession - you should make sure that the user has accepted the microphone permissions in your info.pList sometime before this 
        do {
            try AVAudioSession.sharedInstance().setCategory(.playAndRecord, mode: .default, options: .defaultToSpeaker)
            try AVAudioSession.sharedInstance().setActive(true)

        } catch {
            print(error.debugDescription)
        }
    }

    // 3. recordButton - if the micRecorder is nil start a recording, if not then a recording is currently taking place so stop it 
    @IBAction func recordButtonTapped(_ sender: Any) {
    
        if micRecorder == nil {
    
            startMicRecording()
    
        } else  {
    
            stopMicRecording()
        }
    }

    // *** if the pList Mic Permissions aren't granted then this won't work ***
    func startMicRecording() {

        // 4. create audioSettings
        let myAudioSettings: [String:Any] = [AVFormatIDKey: kAudioFormatMPEG4AAC,
                                                 AVNumberOfChannelsKey: 2,
                                                 AVSampleRateKey: 44100.0,
                                                 AVEncoderBitRateKey: 64000,
                                                 AVEncoderAudioQualityKey: AVAudioQuality.min.rawValue
        ]

        // 5. create a file/url which will be where the recording is stored
        let dirPath = "\(NSTemporaryDirectory())_Recordings_\(UUID().uuidString).m4a"
        let fileURL = URL(fileURLWithPath: dirPath)

        do {

            // 6. initialize the micRecorder with the audio settings from step 4. and the file/url from step 5
            micRecorder = try AVAudioRecorder(url: fileURL, settings: myAudioSettings)

            micRecorder?.prepareToRecord() // 7. prepare the micRecorder

            micRecorder?.delegate = self // 8. set the delegate so that you can access the recording file/url from step 5 once you are done 

            micRecorder?.isMeteringEnabled = true // optional
    
            micRecorder?.record() // 9. call .record() to start recording

        } catch {
            print(error.localizedDescription)
        }
    }
    
    func stopMicRecording() {
    
        micRecorder?.stop() // 10. call .stop() to stop the recording. At this point the delegate methods from step 12/13/17 will be where the recording output (file/url from step 5) will end up

        micRecorder = nil // 11. set the micRecorder to nil
    }
}

// 12. set the AVAudioRecorderDelegate which is the .delegate = self from step 8
extension ViewController: AVAudioRecorderDelegate {

    // your recording should end up here
    func audioRecorderDidFinishRecording(_ recorder: AVAudioRecorder, successfully flag: Bool) {

        // 13. if the recording was successful this flag will be true
        if flag {

             // 14. the file/url from step 5 which is the recording
             let successfullyRecordedURL = recorder.url

             // 15. add the file/url to the array from step 0.    
             arrOfRecordingUrls.append(successfullyRecordedURL)

        } else {

            // 16. the flag was false something went wrong with the recording ???
        }
    }

    // 17. if an error occurs while encoding it will be reported to the delegate
    func audioRecorderEncodeErrorDidOccur(_ recorder: AVAudioRecorder, error: Error?) {

        guard let error = error else { return }
        print(error.localizedDescription)
    }
}