录制声音文件后，只有 iPad Air 听不到答案

【问题标题】：After record sound file, this can't heard in iPad Air only录制声音文件后，只有 iPad Air 听不到
【发布时间】：2014-02-20 18:10:00
【问题描述】：

我在 Apple Store 中有一款具有录音功能的应用。我迁移到 Xcode 5.0.2 和 SDK 7。除了 iPad Air，我对 iOS 6 或 7 设备的此功能没有任何问题。这是我的录音套路：

+(void) startRecording:(NSString *)fileName :(NSString *)fileType
{   NSError* theError = nil;
BOOL result = YES;

// Init audio with record capability
AVAudioSession *audioSession = [AVAudioSession sharedInstance];
result = [audioSession setCategory:AVAudioSessionCategoryRecord error:&theError];
if (!result)
{
    NSLog(@"setCategory failed %@", theError);
}
result = [audioSession setActive:YES error:nil];
if (!result)
{
    NSLog(@"setActive failed %@", theError);
}

// Verify if you have granted to use microphone. iOS 7 or later
if ([audioSession respondsToSelector:@selector(requestRecordPermission:)]) {
    [audioSession requestRecordPermission:^(BOOL granted) {
        if (granted) {
            // Record Sound
            [self recordNow:fileName :fileType];
        }
        else {
            // Microphone disabled code
            NSLog(@"Microphone is disabled..");

            // We're in a background thread here, so jump to main thread to do UI work.
            dispatch_async(dispatch_get_main_queue(), ^{
                [[[UIAlertView alloc] initWithTitle:@"Microphone Access Denied"
                                             message:@"This app requires access to your device's Microphone.\n\nPlease enable Microphone access for this app in Settings / Privacy / Microphone"
                                            delegate:nil
                                   cancelButtonTitle:@"Dismiss"
                                   otherButtonTitles:nil] show];
            });
        }
    }];
}
else {  // iOS 6 
    // Record sound
    [self recordNow:fileName :fileType];
}
}

// Record Sound
+(void) recordNow:(NSString *)fileName :(NSString *)fileType {
recordEncoding = ENC_AAC;

// Microphone enabled code
if (kDebugMode) {
    NSLog(@"Microphone is enabled..");
}

NSMutableDictionary *recordSettings = [[NSMutableDictionary alloc] initWithCapacity:10];
if(recordEncoding == ENC_PCM)
{
    [recordSettings setObject:[NSNumber numberWithInt: kAudioFormatLinearPCM] forKey: AVFormatIDKey];
    [recordSettings setObject:[NSNumber numberWithFloat:44100.0] 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:44100.0] forKey: AVSampleRateKey];
    [recordSettings setObject:[NSNumber numberWithInt:2] forKey:AVNumberOfChannelsKey];
    [recordSettings setObject:[NSNumber numberWithInt:16] forKey:AVEncoderBitRateKey];
    [recordSettings setObject:[NSNumber numberWithInt: AVAudioQualityHigh] forKey:         AVEncoderAudioQualityKey];
}

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *recDir = [paths objectAtIndex:0];
NSURL *url = [NSURL fileURLWithPath:[NSString stringWithFormat:@"%@/%@.%@", recDir, fileName, fileType]];    
NSError *error = nil;
audioRecorder = [[ AVAudioRecorder alloc] initWithURL:url settings:recordSettings error:&error];

[audioRecorder recordForDuration:[[NSUserDefaults standardUserDefaults] integerForKey:kRecordForDuration]];

}

【问题讨论】：

标签： ipad ios7 avaudiorecorder avaudiosession

【解决方案1】：

在这个网站内进行了大量研究后，我发现了一条非常棒的评论，让我在这里节省了一天的时间： "Now that I've removed the AVEncoderBitRateKey and value, it also works on the 5S."

所以，我只是评论这一行并修复它！

[recordSettings setObject:[NSNumber numberWithInt:16] forKey:AVEncoderBitRateKey];

我又能听到 iPad Air 的录音了！为什么会这样？我还不知道，但它的工作原理，也许你有同样的问题，只是想在这个网站上留下一个关于这个案例的日志。

【讨论】：