尝试使用Jenkins构建MacOs应用时出现错误：
error: -fobjc-arc is not supported on platforms using the legacy runtime
Command /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang failed with exit code 1
** BUILD FAILED **
The following build commands failed:
ProcessPCH /var/folders/cn/n0sjm_hx1pdg92gkg49r3tgc0000gn/C/com.apple.DeveloperTools/6.2-6C131e/Xcode/SharedPrecompiledHeaders/DatabaseBuilder2_Prefix-bvnwqzcnsgjinzgqoundsgsrsuxd/DatabaseBuilder2_Prefix.pch.pch DatabaseBuilder2_Prefix.pch normal i386 objective-c com.apple.compilers.llvm.clang.1_0.compiler
(1 failure)
Build step 'Xcode' marked build as failure
Finished: FAILURE
它看起来像是在运行这个命令（我是从完整的jenkins日志中得到的）：
/usr/bin/xcodebuild -target DatabaseBuilder4 -configuration Release clean build
我可以进入项目目录并从终端运行该命令，它似乎工作。我错过了什么？