iphone - 在 iPhone 上，如何使用 fileHandle 即时下载 mp3 文件？

Question

我正在尝试在我的流应用程序上实现 AudioFileStreamSeek 功能。但我没有办法让它运行。甚至马特·加拉格尔也在他的博客上说道:

Icidentally, the AudioFileStreamSeek function seems completely broken. If you can't get it to work (as I couldn't) just seek to a new point in the file, set discontinuous to true and let AudioFileStream deal with it.

我的代码看起来像这样，但我无法让它工作:

    NSString *path = [[NSString alloc] initWithContentsOfURL: url];

    NSLog(@"url = %@", path);
    SInt64 currentOffset;
    UInt32 flags = 0;

    OSStatus status = AudioFileStreamSeek( audioFileStream, 150, &currentOffset, &flags );
    NSLog(@"Setting next byte offset to: %qi, flags: %d", (long long)currentOffset, flags);

    NSFileHandle *fileHandle = [NSFileHandle fileHandleForReadingAtPath: path];
    // then read data from the new offset set by AudioFileStreamSeek
    [fileHandle seekToFileOffset:currentOffset];
    NSData * data = [fileHandle readDataOfLength:4096];

    NSLog(@"data length %d, bytes %d", [data length], [data bytes]);


    if (discontinuous)
    {
        err = AudioFileStreamParseBytes(audioFileStream, length, bytes, kAudioFileStreamParseFlag_Discontinuity);
        if (err)
        {
            [self failWithErrorCode:AS_FILE_STREAM_PARSE_BYTES_FAILED];
            return;
        }
    }
    else
    {
        err = AudioFileStreamParseBytes(audioFileStream, length, bytes, 0);
        if (err)
        {
            [self failWithErrorCode:AS_FILE_STREAM_PARSE_BYTES_FAILED];
            return;
        }
    }

请帮忙...

Answer 1

缺乏任何其他解决方案，您可以做的就是创建一个 NSConnection，然后当您收到 NSData 时，您可以通过处理收到到 NSConnectionDelegate 的每个新 NSData block 来有效地创建流。 NSConnection 将确保按顺序将其发送给您，因此您不必担心顺序是否正确。但请注意，根据您的应用程序，您可能需要在主应用程序线程之外执行此操作，以便即使下载停止并且您必须重新缓冲，用户仍然可以使用您的应用程序。