1、Multiple commands produce
error: Multiple commands produce
'/Users/galahad/Library/Developer/Xcode/DerivedData/xxxxx-drnrntneloepunakcqbcdycudqeh/Build/Products/Debug-iphoneos/xxxxx.app':
1）Target 'xxxxx' has create directory command with output
'/Users/galahad/Library/Developer/Xcode/DerivedData/xxxxx-drnrntneloepunakcqbcdycudqeh/Build/Products/Debug-iphoneos/xxxxx.app'
2）That command depends on command in Target 'xxxxx': script phase “[CP] Copy Pods Resources”
错误原因：
Xcode 10 默认使用的Build System是New Build System，与Xcode9不同。
解决方法：
1）方法一：移除Target -> Build phase -> Copy Pods Resources -> Output Files ->{TARGET_BUILD_DIR}/{UNLOCALIZED_RESOURCES_FOLDER_PATH} 。这个方法解决不彻底，重新pod install后，这个path会重新出现，需要重新删除。
2）方法二：修改Build System。通过Xcode菜单栏 -> File -> Workspace Setting，将Build System修改为Legacy Build System。
2、Jenkins打包时提示Multiple commands produce...，但真机测试没问题
错误原因：
Jenkins打包时默认使用的是New build system，而不管你Xcode里是如何设置的。
解决方法：
archive时添加xcodebuild指令-UseModernBuildSystem=NO，指定不使用当前的编译系统。参考：How can I use the legacy build system with Xcode 10's xcodebuild？
3、 library not found for -lstdc++.6.0.9
ld: library not found for -lstdc++.6.0.9
clang: error: linker command failed with exit code 1 (use -v to see invocation)
错误原因：
Xcode10中已去除这个library。项目中有用到的话，可以从旧版本Xcode中copy一份过来。
解决方法：
从旧版本Xcode的library复制一份libstdc++.6.0.9.tbd，放到Xcode10对应目录下。
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk/usr/lib（真机）
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk/usr/lib（模拟器）
4、Cycle inside xxxxx; build could produce unreliable results
Cycle inside xxxxx; build could produce unreliable results.
This can usually be resolved by moving the app extension embedding build phase to the end of the list.
Cycle details:xxxxx
解决方法：
根据提示，在Target ->Build Phases下，把Embed APP Extensions移动到列表末尾，问题解决。
5、讯飞语音识别SDK报错
Undefined symbols for architecture arm64:
"_OBJC_CLASS$CNContactStore", referenced from:
objc-class-ref in iflyMSC(IFlyContact.o)
"_OBJC_CLASS$_CNContactFetchRequest", referenced from:
objc-class-ref in iflyMSC(IFlyContact.o)
"_CNContactGivenNameKey", referenced from:
-[IFlyContact fetchContactWithContactStore:] in iflyMSC(IFlyContact.o)
"_CNContactFamilyNameKey", referenced from:
-[IFlyContact fetchContactWithContactStore:] in iflyMSC(IFlyContact.o)
ld: symbol(s) not found for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
错误原因：
找不到与Contact相关的key。
解决方法：
添加Contacts.framework。
