record sound

gistfile1.txt

// set the audio session's category to record
      [[AVAudioSession sharedInstance] setCategory:
       AVAudioSessionCategoryRecord error:nil];  
      
      // find the location of the document directory
      NSArray *paths = NSSearchPathForDirectoriesInDomains(
         NSDocumentDirectory, NSUserDomainMask, YES);
      
      // get the first directory
      NSString *dir = [paths objectAtIndex:0];
      
      // create a name for the file using the current system time
      NSString *filename = [NSString stringWithFormat:@"%f.caf", 
                            [[NSDate date] timeIntervalSince1970]];
      
      // create the path using the directory and file name
      NSString *path = [dir stringByAppendingPathComponent:filename];
      
      // create a new NSMutableDictionary for the record settings        
      NSMutableDictionary *settings = [[NSMutableDictionary alloc] init];
      
      // record using the Apple lossless format
      [settings setValue: [NSNumber
         numberWithInt:kAudioFormatAppleLossless] forKey:AVFormatIDKey];
      
      // set the sample rate to 44100 Hz
      [settings setValue:[NSNumber 
                          numberWithFloat:44100.0] forKey:AVSampleRateKey]; 
      
      // set the number of channels for recording
      [settings setValue:[NSNumber numberWithInt:1] 
                  forKey:AVNumberOfChannelsKey];
      
      // set the bit depth
      [settings setValue:[NSNumber numberWithInt:16] 
                  forKey:AVLinearPCMBitDepthKey];
      
      // set whether the format is big endian
      [settings setValue:[NSNumber numberWithBool:NO] 
                  forKey:AVLinearPCMIsBigEndianKey];
      
      // set whether the audio format is floating point
      [settings setValue:[NSNumber numberWithBool:NO] 
                  forKey:AVLinearPCMIsFloatKey];
      [visualizer clear]; // clear the visualizer
      
      [recorder release]; // release the recorder AVAudioRecorder
      
      // initialize recorder with the URL and settings
      recorder =
         [[AVAudioRecorder alloc] initWithURL:[NSURL fileURLWithPath:path]
         settings:settings error:nil];
      [recorder prepareToRecord]; // prepare the recorder to record
      recorder.meteringEnabled = YES; // enable metering for the recorder
      [recorder record]; // start the recording