Xcode 架构x86_64的未定义符号_OBJC“U类”“U RCCManager”；

此错误会发生，但当我升级到0.55.4时仍然存在

ld: warning: directory not found for option '-L/Users/nick/Library./Developer/Xcode/DerivedData/bioreact-fmazebcdwsflmwcjcomjfrqlztce/Build/Products/Debug-iphonesimulator/React'
Undefined symbols for architecture x86_64:
  "_OBJC_CLASS_$_RCCManager", referenced from:
      objc-class-ref in AppDelegate.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

您可以找到错误的屏幕截图：
控制台：

Xcode:

反应本机信息的输出：

Environment:
  OS: macOS Sierra 10.12.6
  Node: 8.9.4
  Yarn: 1.7.0
  npm: 5.6.0
  Watchman: 4.9.0
  Xcode: Xcode 9.2 Build version 9C40b
  Android Studio: 3.0 AI-171.4443003
Packages: (wanted => installed)
  react: 16.2.0 => 16.2.0
  react-native: 0.53.0 => 0.53.0

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我建议您从目录未找到问题开始。解决这一问题也可能解决缺少符号的问题。@PaulFloyd哪一个Xcode或控制台？@nick您解决了这个问题吗？我现在面临着同样的问题！升级react native core，删除android和ios以及node_模块文件夹。然后从头开始