React Native iOS原生模块下载视频报错：AVAggregateAssetDownloadTask不支持currentRequest

在React Native的iOS原生模块中实现视频下载功能，相同代码在独立iOS应用中可正常运行，但调用原生模块时抛出错误：Exception 'AVAggregateAssetDownloadTask does not support currentRequest property'。

错误调用栈 #

Exception 'AVAggregateAssetDownloadTask does not support currentRequest property' was thrown while invoking downloadVideoUsingUri on target CacheVideoModule with params (
    "https://d14nfbmksdrc0w.cloudfront.net/Doctor_Strange_in_the_Multiverse_of_Madness_Official_Trailer/default.m3u8"
)
callstack: (
    0   CoreFoundation                      0x0000000193984e44 42CCFC7B-FF32-3D25-8F01-CCB2AD843A8B + 40516
    1   libobjc.A.dylib                     0x000000018cb1b8d8 objc_exception_throw + 60
    2   CFNetwork                           0x0000000194c820dc _CFNetworkErrorGetLocalizedDescription + 353964
    3   ExoPlayPOC                          0x00000001052521a0 __55+[FLEXNetworkObserver injectIntoNSURLSessionTaskResume]_block_invoke_2 + 52
    4   ExoPlayPOC                          0x0000000105780ec4 $s18react_native_video23AssetPersistenceManagerC14downloadStream3foryAA0D0C_tF + 1280
    5   ExoPlayPOC                          0x00000001057870a0 $s18react_native_video16CacheVideoModuleC08downloadE8UsingUriyySSF + 828
    6   ExoPlayPOC                          0x00000001057871ec $s18react_native_video16CacheVideoModuleC08downloadE8UsingUriyySSFTo + 60
    7   CoreFoundation                      0x00000001939ef6b4 42CCFC7B-FF32-3D25-8F01-CCB2AD843A8B + 476852
    8   CoreFoundation                      0x000000019399bb1c 42CCFC7B-FF32-3D25-8F01-CCB2AD843A8B + 133916
    9   CoreFoundation                      0x000000019399b534 42CCFC7B-FF32-3D25-8F01-CCB2AD843A8B + 132404
    10  ExoPlayPOC                          0x00000001053c136c -[RCTModuleMethod invokeWithBridge:module:arguments:] + 1744
    11  ExoPlayPOC                          0x00000001053c51b0 _ZN8facebook5reactL11invokeInnerEP9RCTBridgeP13RCTModuleDatajRKN5folly7dynamicEiN12_GLOBAL__N_117SchedulingContextE + 1544
    12  ExoPlayPOC                          0x00000001053c49cc _ZZN8facebook5react15RCTNativeModule6invokeEjON5folly7dynamicEiENK3$_0clEv + 144
    13  ExoPlayPOC                          0x00000001053c4930 ___ZN8facebook5react15RCTNativeModule6invokeEjON5folly7dynamicEi_block_invoke + 28
    14  libdispatch.dylib                   0x000000010850453c _dispatch_call_block_and_release + 32
    15  libdispatch.dylib                   0x0000000108505ff0 _dispatch_client_callout + 20
    16  libdispatch.dylib                   0x000000010850e0a0 _dispatch_lane_serial_drain + 988
    17  libdispatch.dylib                   0x000000010850edc8 _dispatch_lane_invoke + 420
    18  libdispatch.dylib                   0x000000010851bcac _dispatch_workloop_worker_thread + 740
    19  libsystem_pthread.dylib             0x00000001e1bfcdf8 _pthread_wqthread + 288
    20  libsystem_pthread.dylib             0x00000001e1bfcb98 start_wqthread + 8
)

相关代码 #

// 创建AVAssetDownloadURLSession配置
let backgroundConfiguration = URLSessionConfiguration.background(withIdentifier: "AAPL-Identifier")
        
// 初始化AVAssetDownloadURLSession
let assetDownloadURLSession = AVAssetDownloadURLSession(configuration: backgroundConfiguration, assetDownloadDelegate: self, delegateQueue: OperationQueue.main)

let _asset = AVURLAsset(url: URL(string: "https://devstreaming-cdn.apple.com/videos/streaming/examples/bipbop_4x3/bipbop_4x3_variant.m3u8")!)
let preferredMediaSelection = _asset.preferredMediaSelection
guard let task =
   assetDownloadURLSession.aggregateAssetDownloadTask(with: _asset,
                                                      mediaSelections: [preferredMediaSelection],
                                                      assetTitle: "my asset",
                                                      assetArtworkData: nil,
                                                      options:
       [AVAssetDownloadTaskMinimumRequiredMediaBitrateKey: 265_000]) else { return }

task.taskDescription = "1"

task.resume()

从错误栈可明确，问题源于FLEXNetworkObserver在注入NSURLSessionTaskResume逻辑时，访问了AVAggregateAssetDownloadTask不支持的currentRequest属性。以下是具体解决方法：

• 临时关闭FLEX网络监听：如果项目集成了FLEX调试工具，在启动下载任务前调用[FLEXNetworkObserver stopObserving]，下载完成后再调用[FLEXNetworkObserver startObserving]恢复监听。
• 规避FLEX的方法注入：在启动下载任务的代码块前后，临时替换NSURLSessionTask的resume方法实现，跳过FLEX的注入逻辑，示例代码：

  // 保存原始resume方法实现
  let originalResume = class_getInstanceMethod(NSURLSessionTask.self, #selector(NSURLSessionTask.resume))
  let originalImpl = method_getImplementation(originalResume!)
  
  // 自定义resume方法，直接调用原始实现
  let customResume: @convention(block) (NSURLSessionTask) -> Void = { task in
      typealias ResumeBlock = @convention(c) (NSURLSessionTask, Selector) -> Void
      let resumeBlock = unsafeBitCast(originalImpl, to: ResumeBlock.self)
      resumeBlock(task, #selector(NSURLSessionTask.resume))
  }
  let customImpl = imp_implementationWithBlock(customResume as Any)
  method_setImplementation(originalResume!, customImpl)
  
  // 启动下载任务
  task.resume()
  
  // 恢复原始resume方法
  method_setImplementation(originalResume!, originalImpl)
  

• 生产环境移除FLEX依赖：FLEX是调试工具，生产包中不应包含，直接移除即可解决该问题。
• 排查其他调试工具冲突：除FLEX外，Flipper等React Native调试工具也可能hookNSURLSessionTask，可尝试关闭相关网络插件或临时禁用工具。

内容的提问来源于stack exchange，提问作者rahulnainwal107