无法通过 iOS 中的 AVPlayer 播放文档目录中的音乐？

Question

我正在使用 MediaPickerController 选择音乐文件。从选择器中选择音乐文件后，我将文件保存到文档目录。

以下是选择并保存到文档目录的代码

//code to click on music button
- (IBAction)addMusic:(id)sender
{
    MPMediaPickerController *soundPicker=[[MPMediaPickerController alloc] initWithMediaTypes:MPMediaTypeMusic];
    soundPicker.delegate=self;
    soundPicker.allowsPickingMultipleItems=NO;
    [self presentViewController:soundPicker animated:YES completion:nil];
}

- (void)mediaPicker: (MPMediaPickerController *)mediaPicker didPickMediaItems:(MPMediaItemCollection *)mediaItemCollection
{
    NSLog(@"music files delegate called");
    MPMediaItem *item = [[mediaItemCollection items] objectAtIndex:0];
    [self uploadMusicFile:item];
    [self dismissViewControllerAnimated:YES completion:nil];
}

- (void) uploadMusicFile:(MPMediaItem *)song
{
    NSURL *url = [song valueForProperty: MPMediaItemPropertyAssetURL];

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

    AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset: songAsset
                                                                      presetName:AVAssetExportPresetAppleM4A];

    exporter.outputFileType =   @"com.apple.m4a-audio";

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString * myDocumentsDirectory = ([paths count] > 0) ? [paths objectAtIndex:0] : nil;

    [[NSDate date] timeIntervalSince1970];
    NSTimeInterval seconds = [[NSDate date] timeIntervalSince1970];
    NSString *intervalSeconds = [NSString stringWithFormat:@"%0.0f",seconds];

    NSString * fileName = [NSString stringWithFormat:@"%@.mp4",intervalSeconds];

    NSString *exportFile = [myDocumentsDirectory stringByAppendingPathComponent:fileName];

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

    // do the export
    // (completion handler block omitted)
    [exporter exportAsynchronouslyWithCompletionHandler:
     ^{
         int exportStatus = exporter.status;

         switch (exportStatus)
         {
             case AVAssetExportSessionStatusFailed:
             {
                 NSError *exportError = exporter.error;
                 NSLog (@"AVAssetExportSessionStatusFailed: %@", exportError);
                 break;
             }
             case AVAssetExportSessionStatusCompleted:
             {
                 NSLog (@"AVAssetExportSessionStatusCompleted");
                 //music data is NSdata
                 music_data = [NSData dataWithContentsOfFile: [myDocumentsDirectory
                                                               stringByAppendingPathComponent:fileName]];

                 // NSLog(@"Data %@",data);
                 // data = nil;

                 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;
             }
         }
     }];
}

从文档目录播放音乐文件的代码

- (void)musicPlay:(UIGestureRecognizer *)recognizer
{
    if(!isMusicPlaying)
    {
        if([musicFile isEqualToString:@"none"])
        {
            NSLog(@"INSIDE IF");

            UIAlertView *alert=[[UIAlertView alloc]initWithTitle:@"Warning" message:@"No music exist" delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil];

            [alert show];
        }
        else
        {
            NSURL *fileURL;
            NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
            NSString *documentsDirectory = [paths objectAtIndex:0];
            bc.music_upload=[bc.music_upload lastPathComponent];
            NSLog(@"music uplaod is %@",bc.music_upload);
            NSString* path = [documentsDirectory stringByAppendingPathComponent:bc.music_upload];
            BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:path];
            if(fileExists)
            {
                NSLog(@"file already exist");
                fileURL = [NSURL fileURLWithPath:path];
                NSLog(@"file url is %@",fileURL);
            }
            else
            {
                NSLog(@"file already not exist");
                if(![musicFile containsString:@"http://"])
                {
                    musicFile=[IMAGE_BASE_URL stringByAppendingString:musicFile];

                }
                fileURL = [NSURL URLWithString:[IMAGE_BASE_URL stringByAppendingString:musicFile]];
            }

            NSLog(@"file url is %@",fileURL);
            isMusicPlaying=true;
            [self.img_music setImage:[UIImage imageNamed:@"play_stop.png"]];
            playerItem = [AVPlayerItem playerItemWithURL:fileURL];
            player = [AVPlayer playerWithPlayerItem:playerItem];
            //player = [AVPlayer playerWithURL:path];
            [player play];
        }
    }
    else
    {
        isMusicPlaying=false;
        [player pause];
        [self.img_music setImage:[UIImage imageNamed:@"music-icon.png"]];
    }
}

我可以保存文件，当我检查文件目录中是否存在文件时，我可以找到该文件。但我无法播放该文件。我不明白问题出在哪里。是音乐文件或我的音乐播放器代码有问题？ ' 编辑： 我已尝试过此代码，但它使应用程序挂起且无响应。

NSURL *url = [NSURL URLWithString:@"http://sound18.mp3pk.com/pop_remix/ebodf11/ebodf11-15(www.songs.pk).mp3"];

NSData *data = [NSData dataWithContentsOfURL:url];

AVAudioPlayer *audioPlayer = [[AVAudioPlayer alloc] initWithData:data error:nil];

[audioPlayer play];

编辑：

我认为问题在于将 MPMediaItem 转换为 NSdata。因为当我将 MPMediaItem 转换为 NSData 然后我可以将它发送到服务器并在浏览器上播放。但是我尝试使用 AVPlayer 玩然后我遇到了这个问题？

Answer 1

来自Apple article

与资产和项目一样，初始化播放器并不意味着它已准备好播放。您应该观察播放器的状态属性，当它准备好播放时，它会更改为 AVPlayerStatusReadyToPlay。您还可以观察 currentItem 属性以访问为流创建的播放器项目。

将观察者添加到您的播放器

- (void)musicPlay:(UIGestureRecognizer *)recognizer {
    // your player code
    [player addObserver:self forKeyPath:@"status" options:0 context:nil];
}

// Observe for the player status
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {


    if (object == _player && [keyPath isEqualToString:@"status"]) {
        if (_player.status == AVPlayerStatusFailed) {
            NSLog(@"AVPlayer Failed");

        } else if (_player.status == AVPlayerStatusReadyToPlay) {
            NSLog(@"AVPlayerStatusReadyToPlay");
            [_player play];


        } else if (_player.status == AVPlayerItemStatusUnknown) {
            NSLog(@"AVPlayer Unknown");

        }
    }
}

Answer 2

试试这个：

NSURL *url = [NSURL URLWithString:filePath]; // like file:///...
AVAsset *asset = [AVURLAsset URLAssetWithURL:url options:nil];
if (asset) {
    AVPlayerItem *item = [AVPlayerItem playerItemWithAsset:asset];
    AVPlayer *player = [AVPlayer playerWithPlayerItem:item];
    [player play];
}

Answer 3

请确保您导入的是<AudioToolbox/AudioToolbox.h>。

此外，使用 ARC，您必须持有对 AVPlayer 对象的强引用。请尝试声明一个强大的属性。

@property (strong, nonatomic) AVPlayer *player;