Iphone 从url本地保存音频，以便以后播放

如何将url中的音频保存到本地以便以后播放。我可以使用avplayer流式播放音频，但无法在本地保存并稍后播放。我尝试使用AVURLASET。有人能帮我吗

这是我试图在本地保存的代码：

在这里，我使用avplayer播放音频流 //用于在本地保存数据的代码

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请发布您的代码。您可以将音频存储在文档目录中，以便以后播放。当你想播放它时，只需将该路径作为音频url。谢谢你的回复。@ShahPaneri:你是对的。但我无法获取要保存的流数据。它正在avplayer中播放。是否仍然可以从avpalyer获取数据？？

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context

{
    if ([keyPath isEqualToString:@"status"])
    {
        AVPlayerItem * item = (AVPlayerItem *)object;
        if (item.status == AVPlayerItemStatusReadyToPlay)
        {
            NSArray *paths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES);
            NSString *documentsDirectory = [paths objectAtIndex:0];
            NSString *myPathDocs =  [documentsDirectory stringByAppendingPathComponent: @"audio.m4a"];
            asset=player.currentItem.asset;
            NSURL *url1 = [NSURL fileURLWithPath:myPathDocs];
            // 5 - Create exporter
            AVAssetExportSession *assetEx = [[AVAssetExportSession alloc]  initWithAsset:player.currentItem.asset presetName:AVAssetExportPresetAppleM4A];//tried with  asset2 also
            assetEx.outputURL=[NSURL fileURLWithPath:myPathDocs];
            assetEx.outputFileType = AVFileTypeAppleM4A;
            assetEx.shouldOptimizeForNetworkUse = YES;
            [assetEx exportAsynchronouslyWithCompletionHandler:^{
                int status = assetEx.status;
                dispatch_async(dispatch_get_main_queue(), ^{
                    [self exportDidFinish:assetEx];
                });
            }];


        }
    }
}
but there is no file created in the documents directory.