是否可以通过iphonesdk中的3.5mm耳机插孔进行录音

Question

我正在制作一个应用程序，我已经创建了一个用iPhone录制语音的功能，但使用3.5毫米耳机插孔无法录制，只能使用iPhone麦克风。所以请建议我该怎么做。

我的录音代码是：

-(void)recording
{
    [recordBtn setImage:[UIImage imageNamed:@"green_btn.png"] forState:UIControlStateNormal];
    NSLog(@"startRecording");
    inc_Bar=0.0;
    // [self performSelector:@selector(stopRecording) withObject:nil afterDelay:10.0f];
    [self increaseProgressBar];
    progressBarTimer = [NSTimer scheduledTimerWithTimeInterval:recordingLength/1000.0f target:self selector:@selector(increaseProgressBar) userInfo:nil repeats:YES];
    audioRecorder = nil;
    // Init audio with record capability
    AVAudioSession *audioSession = [AVAudioSession sharedInstance];
    [audioSession setCategory:AVAudioSessionCategoryRecord error:nil];
    NSMutableDictionary *recordSettings = [[NSMutableDictionary alloc] initWithCapacity:10];
    if(recordEncoding == ENC_PCM)
    {
        [recordSettings setObject:[NSNumber numberWithInt: kAudioFormatLinearPCM] forKey: AVFormatIDKey];
        [recordSettings setObject:[NSNumber numberWithFloat:sampleRateFloat] forKey: AVSampleRateKey];
        [recordSettings setObject:[NSNumber numberWithInt:2] forKey:AVNumberOfChannelsKey];
        [recordSettings setObject:[NSNumber numberWithInt:16] forKey:AVLinearPCMBitDepthKey];
        [recordSettings setObject:[NSNumber numberWithBool:NO] forKey:AVLinearPCMIsBigEndianKey];
        [recordSettings setObject:[NSNumber numberWithBool:NO] forKey:AVLinearPCMIsFloatKey];
    }
    else
    {
        NSNumber *formatObject;
        switch (recordEncoding) {
            case (ENC_AAC):
                formatObject = [NSNumber numberWithInt: kAudioFormatMPEG4AAC];
                break;
            case (ENC_ALAC):
                formatObject = [NSNumber numberWithInt: kAudioFormatAppleLossless];
                break;
            case (ENC_IMA4):
                formatObject = [NSNumber numberWithInt: kAudioFormatAppleIMA4];
                break;
            case (ENC_ILBC):
                formatObject = [NSNumber numberWithInt: kAudioFormatiLBC];
                break;
            case (ENC_ULAW):
                formatObject = [NSNumber numberWithInt: kAudioFormatULaw];
                break;
            default:
                formatObject = [NSNumber numberWithInt: kAudioFormatAppleIMA4];
        }
        [recordSettings setObject:formatObject forKey: AVFormatIDKey];
        [recordSettings setObject:[NSNumber numberWithFloat:sampleRateFloat] forKey: AVSampleRateKey];
        [recordSettings setObject:[NSNumber numberWithInt:2] forKey:AVNumberOfChannelsKey];
//      [recordSettings setObject:[NSNumber numberWithInt:12800] forKey:AVEncoderBitRateKey];
        [recordSettings setObject:[NSNumber numberWithInt:16] forKey:AVLinearPCMBitDepthKey];
        [recordSettings setObject:[NSNumber numberWithInt: AVAudioQualityHigh] forKey: AVEncoderAudioQualityKey];
    }
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *recDir = [paths objectAtIndex:0];
    NSURL *url = [NSURL fileURLWithPath:[NSString stringWithFormat:@"%@/recordTest.caf", recDir]];
    NSError *error = nil;
    audioRecorder = [[ AVAudioRecorder alloc] initWithURL:url settings:recordSettings error:&error];
    if ([audioRecorder prepareToRecord] == YES){
        [audioRecorder record];
    }else {
        int errorCode = CFSwapInt32HostToBig ([error code]);
        NSLog(@"Error: %@ [%4.4s])" , [error localizedDescription], (char*)&errorCode);
    }
    NSLog(@"recording");
}

谢谢。请帮忙。

Answer 1

基于文档：

如果在设置此属性的值tokAudioSessionOverrideAudioRoute_Speaker时插入了耳机，系统会更改输入和输出的音频路由：输入来自内置麦克风；输出到内置扬声器。