升级Xcode 14.2后React Native iOS应用UI冻结无响应问题

我开发了一款支持多语言的React Native应用，可在Android和iOS平台运行。将Xcode升级至14.2后，iOS端应用启动后出现屏幕冻结、无响应的情况。

Xcode日志信息 #

Thread Performance Checker: Thread running at QOS_CLASS_USER_INTERACTIVE waiting on a lower QoS thread running at QOS_CLASS_DEFAULT. Investigate ways to avoid priority inversions
PID: 97834, TID: 527115
Backtrace
=================================================================
3   planetTube                          0x0000000100c22b1c -[_RCTSRRunLoopThread runLoop] + 44
4   planetTube                          0x0000000100c2284c __49+[NSRunLoop(RCTSRWebSocket) RCTSR_networkRunLoop]_block_invoke + 116
5   libdispatch.dylib                   0x0000000103691d5c _dispatch_client_callout + 16
6   libdispatch.dylib                   0x0000000103693800 _dispatch_once_callout + 80
7   planetTube                          0x0000000100c227b0 +[NSRunLoop(RCTSRWebSocket) RCTSR_networkRunLoop] + 84
8   planetTube                          0x0000000100c1c7ec -[RCTSRWebSocket _connect] + 68
9   planetTube                          0x0000000100c1b590 -[RCTSRWebSocket open] + 300
10  planetTube                          0x0000000100bfd9d0 -[RCTReconnectingWebSocket start] + 148
11  planetTube                          0x0000000100bed3bc -[RCTPackagerConnection init] + 404
12  planetTube                          0x0000000100bed208 __49+[RCTPackagerConnection sharedPackagerConnection]_block_invoke + 36
13  libdispatch.dylib                   0x0000000103691d5c _dispatch_client_callout + 16
14  libdispatch.dylib                   0x0000000103693800 _dispatch_once_callout + 80
15  planetTube                          0x0000000100bed1bc +[RCTPackagerConnection sharedPackagerConnection] + 84
16  planetTube                          0x0000000100c87964 -[RCTDevSettings initialize] + 148
17  planetTube                          0x0000000100bd69d0 -[RCTModuleData _initializeModule] + 96
18  planetTube                          0x0000000100bd6330 -[RCTModuleData setUpInstanceAndBridge:] + 2120
19  planetTube                          0x0000000100bd7de8 -[RCTModuleData instance] + 1168
20  planetTube                          0x0000000100b76f8c -[RCTCxxBridge moduleForName:lazilyLoadIfNecessary:] + 680
21  planetTube                          0x0000000100be0ba0 -[RCTModuleRegistry moduleForName:lazilyLoadIfNecessary:] + 128
22  planetTube                          0x0000000100be0b14 -[RCTModuleRegistry moduleForName:] + 48
23  planetTube                          0x0000000100c9bd64 -[RCTPerfMonitor devMenuItem] + 84
24  planetTube                          0x0000000100c9bc38 -[RCTPerfMonitor initialize] + 88
25  planetTube                          0x0000000100bd69d0 -[RCTModuleData _initializeModule] + 96
26  planetTube                          0x0000000100bd6330 -[RCTModuleData setUpInstanceAndBridge:] + 2120
27  planetTube                          0x0000000100bd8018 __25-[RCTModuleData instance]_block_invoke + 44
28  planetTube                          0x0000000100c409dc RCTUnsafeExecuteOnMainQueueSync + 52
29  planetTube                          0x0000000100bd7c88 -[RCTModuleData instance] + 816
30  planetTube                          0x0000000100b7b7f8 __49-[RCTCxxBridge _prepareModulesWithDispatchGroup:]_block_invoke + 156
31  libdispatch.dylib                   0x0000000103690594 _dispatch_call_block_and_release + 24
32  libdispatch.dylib                   0x0000000103691d5c _dispatch_client_callout + 16
33  libdispatch.dylib                   0x00000001036a2978 _dispatch_main_queue_drain + 1684
34  libdispatch.dylib                   0x00000001036a22d4 _dispatch_main_queue_callback_4CF + 40
35  CoreFoundation                      0x0000000180372ca4 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 12
36  CoreFoundation                      0x000000018036d360 __CFRunLoopRun + 1956
37  CoreFoundation                      0x000000018036c7a4 CFRunLoopRunSpecific + 584
38  GraphicsServices                    0x0000000188ff7c98 GSEventRunModal + 160
39  UIKitCore                           0x000000010ee2237c -[UIApplication _run] + 868
40  UIKitCore                           0x000000010ee26374 UIApplicationMain + 124
41  planetTube                          0x00000001008a214c main + 100
2023-03-19 14:05:21.846279+0530 planetTube[97834:527225] [connection] nw_socket_handle_socket_event [C5.1.1:1] Socket SO_ERROR [61: Connection refused]
2023-03-19 14:05:21.847297+0530 planetTube[97834:527225] [connection] nw_socket_handle_socket_event [C5.1.2:1] Socket SO_ERROR [61: Connection refused]
2023-03-19 14:05:21.847706+0530 planetTube[97834:527231] [connection] nw_connection_get_connected_socket_block_invoke [C5] Client called nw_connection_get_connected_socket on unconnected nw_connection
2023-03-19 14:05:21.847810+0530 planetTube[97834:527231] TCP Conn 0x6000007f4000 Failed : error 0:61 [61]
2023-03-19 14:05:22.307289+0530 planetTube[97834:527223] [native] Manifest does not exist - creating a new one.

(null)
2023-03-19 14:05:22.386170+0530 planetTube[97834:527115] [native] [GESTURE HANDLER] Initialize gesture handler for view <RCTRootContentView: 0x12c50af90; reactTag: 1; frame = (0 0; 393 852); gestureRecognizers = <NSArray: 0x6000038e3bd0>; layer = <CALayer: 0x6000036c0500>>

问题分析 #

从日志能定位两个核心问题：

1. 线程优先级倒置：负责用户交互的主线程（QOS_CLASS_USER_INTERACTIVE）正在等待一个默认优先级（QOS_CLASS_DEFAULT）的网络线程，直接导致主线程阻塞，应用失去响应。
2. WebSocket连接失败：日志显示Socket连接被拒绝（错误61），这是Debug模式下应用尝试连接Metro打包服务失败导致的，进一步加重了主线程的阻塞情况。

解决方案 #

• 区分环境初始化开发模块：在非Debug环境下，禁用RCTPackagerConnection、RCTPerfMonitor等开发相关模块的初始化，避免主线程等待失败的WebSocket连接。可在AppDelegate中添加环境判断逻辑，仅在Debug模式下初始化这些模块。
• 确保Debug环境Metro服务正常：启动应用前先运行npx react-native start，保证打包服务可用；同时检查iOS网络配置，在Info.plist中添加NSAppTransportSecurity例外，允许HTTP连接到本地Metro服务。
• 修复线程优先级：修改React Native源码中_RCTSRRunLoopThread的线程优先级，将其QoS等级设置为QOS_CLASS_USER_INTERACTIVE或QOS_CLASS_UTILITY，避免主线程等待低优先级线程。
• 升级React Native版本：旧版本React Native可能存在与Xcode 14.2的兼容性问题，升级到最新稳定版可修复这类线程阻塞和初始化异常。
• 清理各类缓存：执行以下命令排除缓存导致的问题：

  # 清理iOS Pod缓存
  pod deintegrate && pod install
  # 清理React Native缓存
  npx react-native start --reset-cache
  

  同时通过Xcode快捷键Cmd + Shift + K清理Xcode缓存。

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