IPhone之AVAudioRecorder

#import <AVFoundation/AVFoundation.h>  需要引入
 
//获取document目录的路径
[cpp] - (NSString*) documentsPath { 
 if (! _documentsPath) { 
  NSArray *searchPaths = 
   NSSearchPathForDirectoriesInDomains 
   (NSDocumentDirectory, NSUserDomainMask, YES); 
  _documentsPath = [searchPaths objectAtIndex: 0]; 
  [_documentsPath retain]; 
 } 
 return _documentsPath; 
} 
  
//(document目录的路径)  
 NSString *destinationString = [[self documentsPath] 
   stringByAppendingPathComponent:filenameField.text]; 
 NSURL *destinationURL = [NSURL fileURLWithPath: destinationString]; 
//初始化AVAudioRecorder  
 NSError *recorderSetupError = nil; 
 AVAudioRecorder audioRecorder = [[AVAudioRecorder alloc] initWithURL:destinationURL 
   settings:recordSettings error:&recorderSetupError]; 
 [recordSettings release]; 
- (NSString*) documentsPath {
 if (! _documentsPath) {
  NSArray *searchPaths =
   NSSearchPathForDirectoriesInDomains
   (NSDocumentDirectory, NSUserDomainMask, YES);
  _documentsPath = [searchPaths objectAtIndex: 0];
  [_documentsPath retain];
 }
 return _documentsPath;
}
 
//(document目录的路径)
 NSString *destinationString = [[self documentsPath]
   stringByAppendingPathComponent:filenameField.text];
 NSURL *destinationURL = [NSURL fileURLWithPath: destinationString];
//初始化AVAudioRecorder
 NSError *recorderSetupError = nil;
 AVAudioRecorder audioRecorder = [[AVAudioRecorder alloc] initWithURL:destinationURL
   settings:recordSettings error:&recorderSetupError];
 [recordSettings release];

 
第二个参数  settings是一个容纳键值对的NSDictionary有四种一般的键
1:一般的音频设置
2:线性PCM设置
3:编码器设置
4:采样率转换设置
 
NSMutableDictionary  需要加入五个设置值(线性PCM)
[java] NSMutableDictionary *recordSettings = 
  [[NSMutableDictionary alloc] initWithCapacity:10]; 
  //1 ID号  
  [recordSettings setObject: 
   [NSNumber numberWithInt: kAudioFormatLinearPCM] forKey: AVFormatIDKey]; 
  float sampleRate = 
   [pcmSettingsViewController.sampleRateField.text floatValue]; 
  //2 采样率  
  [recordSettings setObject: 
   [NSNumber numberWithFloat:sampleRate] forKey: AVSampleRateKey]; 
    
  //3 通道的数目  
  [recordSettings setObject: 
   [NSNumber numberWithInt: 
    (pcmSettingsViewController.stereoSwitch.on ? 2 : 1)] 
   forKey:AVNumberOfChannelsKey]; 
  int bitDepth = 
   [pcmSettingsViewController.sampleDepthField.text intValue]; 
    
  //4 采样位数  默认 16  
  [recordSettings setObject: 
   [NSNumber numberWithInt:bitDepth] forKey:AVLinearPCMBitDepthKey]; 
    
  //5  
  [recordSettings setObject: 
   [NSNumber numberWithBool: 
     pcmSettingsViewController.bigEndianSwitch.on] 
    forKey:AVLinearPCMIsBigEndianKey]; 
  
  //6 采样信号是整数还是浮点数  
  [recordSettings setObject: 
   [NSNumber numberWithBool: 
   &nb