IOS出现文件引用错误，找不到文件，可以试试

Showing All Errors Only

Ld /Users/zhanghairui/Library/Developer/Xcode/DerivedData/KnowledgeService-ewnxzxvqbpgosbbmupfmjqbkonez/Build/Products/Debug-iphonesimulator/KnowledgeService.app/KnowledgeService normal x86_64

cd /Users/zhanghairui/Desktop/KnowledgeService

export IPHONEOS_DEPLOYMENT_TARGET=8.0

export PATH="/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin:/Applications/Xcode.app/Contents/Developer/usr/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin"

/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -arch x86_64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator11.1.sdk -L/Users/zhanghairui/Library/Developer/Xcode/DerivedData/KnowledgeService-

解决方式如下：

先退出xcode，再把/Users/appleapple/Library/Developer/Xcode/DerivedData/下面的东西都删除（DerivedData本身不要删），再启动xcode，再rebuild.