Question

我正在开发音乐应用程序，我需要将转换后的歌曲存储到“文档目录”以供以后使用。由于某种原因，它不是从存储的目录URL播放，但我也没有收到任何错误。我在目录中检查并发现其中存在相同的存储歌曲。

之前在目录中成功播放了相同的歌曲网址。

我的代码，用于在从mp3转换为m4a后存储歌曲。

{
NSURL *assetURL = [NSURL URLWithString:_assertURL];
    AVURLAsset *songAsset = [AVURLAsset URLAssetWithURL:assetURL options:nil];

    /* approach 1: export just the song itself
     */
    AVAssetExportSession *exporter = [[AVAssetExportSession alloc]
                                      initWithAsset: songAsset
                                      presetName: AVAssetExportPresetAppleM4A];
    NSLog (@"created exporter. supportedFileTypes: %@", exporter.supportedFileTypes);
    exporter.outputFileType = @"com.apple.m4a-audio";
    NSString *exportFile = [myDocumentsM4aDirectory() stringByAppendingPathComponent: [NSString stringWithFormat:@"%@.m4a",_title]];
    // end of approach 1

    // set up export (hang on to exportURL so convert to PCM can find it)
    [self myDeleteFile:exportFile];
    //[exportURL release];
    _exportURL = [NSURL fileURLWithPath:exportFile];
    exporter.outputURL = _exportURL;

    // do the export
    [exporter exportAsynchronouslyWithCompletionHandler:^{
        int exportStatus = exporter.status;
        switch (exportStatus) {
            case AVAssetExportSessionStatusFailed: {
                // log error to view
                NSError *exportError = exporter.error;
                NSLog (@"AVAssetExportSessionStatusFailed: %@", exportError);

                break;
            }
            case AVAssetExportSessionStatusCompleted: {
                NSLog (@"AVAssetExportSessionStatusCompleted");

 //Final document url

                NSURL *audioUrl = _exportURL;
                NSLog(@"Audio Url=%@",audioUrl);


                break;
            }
            case AVAssetExportSessionStatusUnknown: {
                NSLog (@"AVAssetExportSessionStatusUnknown");


                break;
            }
            case AVAssetExportSessionStatusExporting: {
                NSLog (@"AVAssetExportSessionStatusExporting");


                break;
            }
            case AVAssetExportSessionStatusCancelled: {
                NSLog (@"AVAssetExportSessionStatusCancelled");


                break;
            }
            case AVAssetExportSessionStatusWaiting: {
                NSLog (@"AVAssetExportSessionStatusWaiting");

                break;
            }
            default: {
                NSLog (@"didn't get export status");


                break;
            }
        }
    }];

}

删除当前路径中可用的现有文件：

- (void)myDeleteFile:(NSString*)path{

    if ([[NSFileManager defaultManager] fileExistsAtPath:path]) {
        NSError *deleteErr = nil;
        [[NSFileManager defaultManager] removeItemAtPath:path error:&deleteErr];
        if (deleteErr) {
            NSLog (@"Can't delete %@: %@", path, deleteErr);
        }
    }

}

这是用于创建m4a目录的代码：

NSString* myDocumentsM4aDirectory(){

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

    NSError *error = nil;
    NSString *dataPath = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"/m4aFolder"];

    if (![[NSFileManager defaultManager] fileExistsAtPath:dataPath])
        [[NSFileManager defaultManager] createDirectoryAtPath:dataPath withIntermediateDirectories:NO attributes:nil error:&error];
    //Create folde
    return dataPath;


}

如何找出这个问题永久播放本地存储的歌曲？

编辑：

//以下函数调用播放歌曲

- (void)playSong
{
AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:[NSURL fileURLWithPath:_exportURL] options:nil];
NSError *error = nil;
AVAudioPlayer *player = [[AVAudioPlayer alloc]initWithContentsOfURL:asset.URL error:&error];
if(error == nil)
{
[player play]
}else
{
NSLog (@"Error during playing: %@", error);
}

}

谢谢，

答案：我找到了没有从文档播放的歌曲的解决方案，因为我之前将整个断言URL存储到核心数据。文件ID“xxxxxx-xxxxxxx-xxxxxxx-xxxxxxxxx”将在每次发布时保持不变。

所以，我正在根据之前附加到URL的标题和扩展名获取断言路径。现在它的工作正常。

此回答有助于解决此问题：Play local audio file with AVAudioPlayer

Answer 1

You can play song directly from document directory 

url = [NSURL fileURLWithPath:strFilePath];

        NSError *error;
        if(mp3player)
        {
            mp3player = nil;
        }
        mp3player = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:&error];
        mp3player.delegate = self;
        [mp3player setVolume:1.0];
        mp3player.numberOfLoops = 0;
        [mp3player prepareToPlay];
        [mp3player play];

注意：

在.h文件中定义“mp3player”。

从Device本地文档URL到AVAudioPlayer

1 个答案: