{"id":3525,"date":"2012-12-09T15:29:47","date_gmt":"2012-12-09T10:29:47","guid":{"rendered":"http:\/\/aasims.wordpress.com\/?p=3525"},"modified":"2025-04-09T12:23:21","modified_gmt":"2025-04-09T12:23:21","slug":"how-to-record-audio-in-ios-application","status":"publish","type":"post","link":"https:\/\/aasimnaseem.com\/blog\/how-to-record-audio-in-ios-application\/","title":{"rendered":"How to record Audio in iOS Application"},"content":{"rendered":"

Hello dev mate;\"XcodeLogo\"<\/a>
\nHope you had a good weekend and refreshing Monday;<\/p>\n

Today we’ll learn how to record audio in iOS application; Now a days, I’m working on an application where I need to record voice of user for some processing; I tried some framework classes from iOS sdk in a test project and here are my findings;<\/p>\n

So lets start;<\/p>\n


\nPriminarly we’ll use following classes and framework<\/p>\n

AVFoundation.framwork
\n<\/strong>Provides set of APIs to record\/play audio and video in iOS application;<\/p>\n

AVAudioRecorder
\n<\/strong>Called an audio recorder, provides audio recording capability in your application.<\/p>\n

AVAudioPlayer
\n<\/strong>An instance of the AVAudioPlayer class called an audio player, provides playback of audio data from a file or memory;<\/p>\n

1. Project Creation and Setup<\/strong><\/h3>\n

1. Open you Xcode and create new project .i.e. File -> New -> New Project or \u00a0press Command+Shift+N<\/p>\n

2. Create\u00a0Single View Application<\/em>\u00a0and\u00a0<\/em>provide suitable name; In my case, its\u00a0AudioRecordingExample<\/em>;<\/p>\n

3. Select project location etc and save it; Your project should look like this<\/p>\n

\"Screen<\/a><\/p>\n

4. Add required framework to your project .i.e. AVFoundation; For this select your project in Navigator, then select Target at right sight panel; Go to\u00a0Build Phases,\u00a0<\/em>chose\u00a0Linke Binary with Libraries; <\/em>Press\u00a0+<\/em>\u00a0button from botom and chose AVFoundation<\/em>\u00a0from list;<\/p>\n

\"Screen<\/a><\/p>\n

After adding framework, you libraries should look like this;<\/p>\n

\"Screen<\/a><\/p>\n

2. Interface Design<\/strong><\/h3>\n

First open the ViewController.xib file and make your screen like this; I’m sure I don’t need to explain how to design it; (:<\/p>\n

\"Screen<\/a><\/strong><\/p>\n

3. Declaring Variable in .h file;<\/strong><\/h3>\n

Open you ViewController.h file from Navigator and add the following code there;<\/p>\n

Implement the following\u00a0AVAudioRecorderDelegate and AVAudioPlayerDelegate in your \u00a0viewController;<\/p>\n

[code lang=”objc”]<\/p>\n

@interface ViewController : UIViewController <AVAudioRecorderDelegate, AVAudioPlayerDelegate><\/p>\n

[\/code]<\/p>\n

Include AVFoundation.h in your import section;<\/p>\n

[code lang=”objc”]<\/p>\n

#import <AVFoundation\/AVFoundation.h><\/p>\n

[\/code]<\/p>\n

Add the following two variables, and four UIButtons in your viewController;<\/p>\n

[code lang=”objc”]
\n\/\/for recording section
\nAVAudioRecorder *audioRecorder;
\nIBOutlet UIButton *recordingButton;
\nIBOutlet UIButton *stopRecordingButton;
\n\/\/for playback section
\nAVAudioPlayer *audioPlayer;
\nIBOutlet UIButton *playButton;
\nIBOutlet UIButton *stopPlayingButton;
\n[\/code]<\/p>\n

The name of variables are enough to describe their usage in our program; Bind the outlets with respective buttons on xib file;<\/p>\n

Now add following methods in your .h file<\/p>\n

[code lang=”objc”]
\n-(IBAction) recordAudio;
\n-(IBAction) stopRecording;
\n-(IBAction) playAudio;
\n-(IBAction) stopPlaying;
\n[\/code]<\/p>\n

4. Your .m file, actual code<\/strong><\/h3>\n

Add the following code in your viewDidLoad method<\/p>\n

[code lang=”objc” wraplines=”false”]
\n– (void)viewDidLoad {
\n[super viewDidLoad];
\naudioRecorder.delegate = self;
\naudioPlayer.delegate = self;
\nplayButton.enabled = NO;
\nstopPlayingButton.enabled = NO;
\nNSArray *dirPaths;
\nNSString *docsDir;
\ndirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
\ndocsDir = [dirPaths objectAtIndex:0];
\nNSString *soundFilePath = [docsDir stringByAppendingPathComponent:@”sound.caf”];
\nNSURL *soundFileURL = [NSURL fileURLWithPath:soundFilePath];
\nNSDictionary *recordSettings = [NSDictionary dictionaryWithObjectsAndKeys:
\n[NSNumber numberWithInt:AVAudioQualityMin], AVEncoderAudioQualityKey,
\n[NSNumber numberWithInt:16], AVEncoderBitRateKey,
\n[NSNumber numberWithInt: 2], AVNumberOfChannelsKey,
\n[NSNumber numberWithFloat:44100.0], AVSampleRateKey,
\nnil];
\nNSError *error = nil;
\naudioRecorder = [[AVAudioRecorder alloc] initWithURL:soundFileURL
\nsettings:recordSettings
\nerror:&error];
\nif (error){
\nNSLog(@”error: %@”, [error localizedDescription]);
\n} else {
\n[audioRecorder prepareToRecord];
\n}
\n}
\n[\/code]<\/p>\n

Now add the action methods, bind with each UIButton over screen;<\/p>\n

[code lang=”objc” wraplines=”false”]
\n-(IBAction) recordAudio{
\nif (!audioRecorder.recording){
\nplayButton.enabled = NO;
\nstopRecordingButton.enabled = YES;
\n[audioRecorder record];
\n}
\n}
\n\/\/——————————————————————————————-
\n-(IBAction)stopRecording{
\nstopRecordingButton.enabled = NO;
\nplayButton.enabled = YES;
\nrecordingButton.enabled = YES;
\nif (audioRecorder.recording){
\n[audioRecorder stop];
\n}
\n}
\n\/\/——————————————————————————————-
\n-(IBAction) stopPlaying{
\nif (audioPlayer.playing) {
\n[audioPlayer stop];
\n}
\n}
\n\/\/——————————————————————————————-
\n-(IBAction) playAudio{
\nif (!audioRecorder.recording){
\nstopPlayingButton.enabled = YES;
\nrecordingButton.enabled = NO;
\nNSError *error;
\naudioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:audioRecorder.url error:&error];
\naudioPlayer.delegate = self;
\nif (error)
\nNSLog(@”Error: %@”, [error localizedDescription]);
\nelse
\n[audioPlayer play];
\n}
\n}
\n[\/code]<\/p>\n

You can also implement these delegate methods, though to keep the tutorial simple, I’m not using them wisely here;<\/p>\n

[code lang=”objc” wraplines=”false”]<\/p>\n

-(void)audioPlayerDidFinishPlaying: (AVAudioPlayer *)player successfully:(BOOL)flag{
\nrecordingButton.enabled = YES;
\nstopPlayingButton.enabled = NO;
\n}
\n\/\/——————————————————————————————-
\n-(void)audioPlayerDecodeErrorDidOccur:(AVAudioPlayer *)player error:(NSError *)error{
\nNSLog(@”Decode Error occurred”);
\n}
\n\/\/——————————————————————————————-
\n-(void)audioRecorderDidFinishRecording: (AVAudioRecorder *)recorder successfully:(BOOL)flag{
\nNSLog(@”Audio Player has finished recording”);
\n}
\n\/\/——————————————————————————————-
\n-(void)audioRecorderEncodeErrorDidOccur: (AVAudioRecorder *)recorder error:(NSError *)error{
\nNSLog(@”Encode Error occurred”);
\n}
\n\/\/——————————————————————————————-<\/p>\n

[\/code]<\/p>\n

And we are good to go now; Just run the code, tap Record in recording section and speak something in your microphone; Hit stop and press Play in playback section; You’ll hear yourself for sure;<\/p>\n

The audio file has saved in \/Document\u00a0directory\u00a0of your project, and you can get its content by following code, for further uses;<\/p>\n

[code lang=”objc” wraplines=”false”]
\nNSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
\nNSString *documentsDirectory = [paths objectAtIndex:0];
\nNSString *filePath = [documentsDirectory stringByAppendingPathComponent:<your_file_name>];
\nNSData *fileContents = [NSData dataWithContentsOfFile:filePath];
\n[\/code]<\/p>\n

Thats it; You have done infact;<\/p>\n

Now its time to look some new concepts; Back to code when we initialized our AVAudioRecorder instance, we provide it a dictionary of setting, as given below<\/p>\n

[code lang=”objc” wraplines=”false”]
\nNSDictionary *recordSettings = [NSDictionary dictionaryWithObjectsAndKeys:
\n[NSNumber numberWithInt:AVAudioQualityMin], AVEncoderAudioQualityKey,
\n[NSNumber numberWithInt:16], AVEncoderBitRateKey,
\n[NSNumber numberWithInt: 2], AVNumberOfChannelsKey,
\n[NSNumber numberWithFloat:44100.0], AVSampleRateKey,
\nnil];
\nNSError *error = nil;
\naudioRecorder = [[AVAudioRecorder alloc] initWithURL:soundFileURL settings:recordSettings error:&error];
\n[\/code]<\/p>\n

This dictionary is holding the different parameters for the audio we are going to capture and record; It inclues Bit rate, Sample rate, Number of channels etc; Let discuss them one by one in a concise way;<\/p>\n

Bit Rate<\/strong>
\nBitrate refers to the number of bits\u2014or the amount of data\u2014that are processed over a certain amount of time; In audio, this usually means kilobits per second; For example, if you have a song with bitrate of 256 kilobits per second, meaning there are 256 kilobits of data stored in every second of a song; Multiply the bitrate with length of your song and you’ll get the file size; The higher the bitrate of a track, the more space it will take up on your computer;<\/p>\n

Audio Channel<\/strong>
\nA channel in audio is just one separate stream of audio information; Mono audio sources have one channel, Stereo sources have two (left and right), or in more simple words Mono is 1 audio channel (You hear the same sound in both ears) where as Stereo is 2 audio channels (Each headphone can hear a different sound)
\nNow a days, the normally 5.1 audio channel are being use, having five normal audio channels (Left, Center, Right, Left Surround, Right Surround)<\/p>\n

Sample Rate<\/strong>
\nSample rate is the number of samples of audio carried per second; In simple words it is a frequency of audio; Data equal to bit rate is passed to processor to generate sample rates (audio frequency); More sample rate means more frequency and hence more clear, smooth audio listening experience;
\n44.1 kHz is the sampling rate of audio CDs giving a 20 kHz maximum frequency; 20 kHz is the highest frequency generally audible by humans, so making 44.1 kHz the logical choice for most audio material.<\/p>\n

Read the code again for initializing the AVAudioRecorder instance; Hope this time you’ll have better understanding;<\/p>\n

Happy coding; (:<\/p>\n

\"Flag<\/p>\n","protected":false},"excerpt":{"rendered":"

Hello dev mate; Hope you had a good weekend and refreshing Monday; Today we’ll learn how to record audio in iOS application; Now a days, I’m working on an application where I need to record voice of user for some processing; I tried some framework classes from iOS sdk in…<\/p>\n","protected":false},"author":1,"featured_media":4551,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[22],"tags":[178,179,180,507,554,1076,1117],"class_list":["post-3525","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-ios","tag-avaudioplayer","tag-avaudiorecorder","tag-avfoundation","tag-how-to-recored-audio-in-iphone","tag-iphone","tag-voice-recording","tag-xcode"],"_links":{"self":[{"href":"https:\/\/aasimnaseem.com\/blog\/wp-json\/wp\/v2\/posts\/3525","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/aasimnaseem.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/aasimnaseem.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/aasimnaseem.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/aasimnaseem.com\/blog\/wp-json\/wp\/v2\/comments?post=3525"}],"version-history":[{"count":2,"href":"https:\/\/aasimnaseem.com\/blog\/wp-json\/wp\/v2\/posts\/3525\/revisions"}],"predecessor-version":[{"id":4552,"href":"https:\/\/aasimnaseem.com\/blog\/wp-json\/wp\/v2\/posts\/3525\/revisions\/4552"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/aasimnaseem.com\/blog\/wp-json\/wp\/v2\/media\/4551"}],"wp:attachment":[{"href":"https:\/\/aasimnaseem.com\/blog\/wp-json\/wp\/v2\/media?parent=3525"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/aasimnaseem.com\/blog\/wp-json\/wp\/v2\/categories?post=3525"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/aasimnaseem.com\/blog\/wp-json\/wp\/v2\/tags?post=3525"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}