Question

我正在创建一个音乐应用程序，用户可以在其中访问ios音乐库并将歌曲保存到其应用程序（即文档目录）。我可以使用MPMediaPickerController访问音乐库，但不知道如何处理其委托方法，以便将选定的歌曲保存到我的文档目录。目前我正在使用此代码

- (void) mediaPicker: (MPMediaPickerController *) mediaPicker
   didPickMediaItems: (MPMediaItemCollection *) collection
{
    [self dismissViewControllerAnimated:YES completion:nil];
    [self playSelectedMediaCollection: collection];
}


- (void) playSelectedMediaCollection: (MPMediaItemCollection *) collection {

    if (collection.count == 1) {
        NSArray *items = collection.items;
        MPMediaItem *mediaItem =  [items objectAtIndex:0];
        [self mediaItemToData:mediaItem];
    }
}



-(void)mediaItemToData:(MPMediaItem*)mediaItem
{
    // Implement in your project the media item picker

    MPMediaItem *curItem = mediaItem;//musicPlayer.nowPlayingItem;

    NSURL *url = [curItem valueForProperty: MPMediaItemPropertyAssetURL];

    AVURLAsset *songAsset = [AVURLAsset URLAssetWithURL: url options:nil];

    AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset: songAsset
                                                                      presetName: AVAssetExportPresetPassthrough];

    exporter.outputFileType = @"public.mpeg-4";

    NSString *exportFile = [[self myDocumentsDirectory] stringByAppendingPathComponent:
                            @"exported.mp4"];

    NSURL *exportURL = [NSURL fileURLWithPath:exportFile] ;
    exporter.outputURL = exportURL;



    NSData *data = [NSData dataWithContentsOfFile: [[self myDocumentsDirectory]
                                                    stringByAppendingPathComponent: @"exported.mp4"]];
//    
//    NSLog(@"%@",data);
//    NSURL *audioUrl = exportURL;
//    NSLog(@"Audio Url=%@",audioUrl);
//    audioData = [NSData dataWithContentsOfURL:audioUrl];
//    NSLog(@"%@",audioData);
    // Do with data something
    // do the export
    // (completion handler block omitted)
    [exporter exportAsynchronouslyWithCompletionHandler:
     ^{
//         int exportStatus=exporter.status;
         NSLog(@"%d export status",exporter.status);
         if (exporter.status==AVAssetExportSessionStatusCompleted)
         {
             NSLog(@"successfull");
         }
         NSData *data = [NSData dataWithContentsOfFile: [[self myDocumentsDirectory]
                                                         stringByAppendingPathComponent: @"exported.mp4"]];

         NSURL *audioUrl = exportURL;
         NSLog(@"Audio Url=%@",audioUrl);
        audioData = [NSData dataWithContentsOfURL:audioUrl];
         NSLog(@"%@",audioData);
         // Do with data something

     }];
}

在上面的代码中，调试器永远不会出现在导出会话异步块中。如果上述代码中有任何修改，或者您有任何可用的代码可用于我的要求，请告诉我。谢谢......

Answer 1

我认为错过了

/

试试这段代码

NSString *exportFile = [[self myDocumentsDirectory] stringByAppendingPathComponent: @"/exported.mp4"];

<强>已更新

或原因可以是您使用的预设名称

/ *此导出选项将导致所有轨道的媒体完全按照源资源中的存储方式传递到输出，但通道无法通过的轨道，通常是由于指定的outputFileType指示的容器格式的约束。此选项不包含在-allExportPresets和-exportPresetsCompatibleWithAsset返回的数组中。 * / AVF_EXPORT NSString * const AVAssetExportPresetPassthrough NS_AVAILABLE（10_7,4_0）;

这里有关于exportAsynchronouslyWithCompletionHandler的良好描述：https://developer.apple.com/library/mac/documentation/AVFoundation/Reference/AV‌AssetExportSession_Class/Reference/Reference.html

Answer 2

适用于Swift 3.0或4

func mediaPicker(_ mediaPicker: MPMediaPickerController, didPickMediaItems mediaItemCollection: MPMediaItemCollection) {
    mediaPicker.dismiss(animated: true) {

        print("You selected \(mediaItemCollection)")

        let item: MPMediaItem = mediaItemCollection.items[0]
        let pathURL: URL? = item.value(forProperty: MPMediaItemPropertyAssetURL) as? URL
        if pathURL == nil {
            print("Picking Error")
            return
        }

        // get file extension andmime type
        let str = pathURL!.absoluteString
        let str2 = str.replacingOccurrences( of : "ipod-library://item/item", with: "")
        let arr = str2.components(separatedBy: "?")
        var mimeType = arr[0]
        mimeType = mimeType.replacingOccurrences( of : ".", with: "")

        // Export the ipod library as .m4a file to local directory for remote upload
        let exportSession = AVAssetExportSession(asset: AVAsset(url: pathURL!), presetName: AVAssetExportPresetAppleM4A)
        exportSession?.shouldOptimizeForNetworkUse = true
        exportSession?.outputFileType = AVFileTypeAppleM4A

        let documentURL = try! FileManager.default.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: true)
        let outputURL = documentURL.appendingPathComponent("custom.m4a")

        //Delete Existing file
        do {
            try FileManager.default.removeItem(at: outputURL)
        } catch let error as NSError {
            print(error.debugDescription)
        }

        exportSession?.outputURL = outputURL
        exportSession?.exportAsynchronously(completionHandler: { () -> Void in

            if exportSession!.status == AVAssetExportSessionStatus.completed  {
                print("Export Successfull")
            }

        })

    }

}

将歌曲保存到ios音乐库中的文档目录

2 个答案: