我有这个错误：
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/clang -x objective-c-header -arch i386 -fmessage-length=0 -pipe -fdiagnostics-print-source-range-info -std=gnu99 -Wno-trigraphs -fpascal-strings -O0 -mdynamic-no-pic -Wreturn-type -Wunused-variable -Wuninitialized -DDEBUG=1 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator5.1.sdk -fexceptions -fasm-blocks -mmacosx-version-min=10.6 -gdwarf-2 -fobjc-abi-version=2 -fobjc-legacy-dispatch -D__IPHONE_OS_VERSION_MIN_REQUIRED=50100 -iquote "/Users/leti/Library/Developer/Xcode/DerivedData/qsdfghj$`-douqygbrghbbyeevylooywioybsq/Build/Intermediates/qsdfghj$`.build/Debug-iphonesimulator/qsdfghj$`.build/qsdfghj$`-generated-files.hmap" "-I/Users/leti/Library/Developer/Xcode/DerivedData/qsdfghj$`-douqygbrghbbyeevylooywioybsq/Build/Intermediates/qsdfghj$`.build/Debug-iphonesimulator/qsdfghj$`.build/qsdfghj$`-own-target-headers.hmap" "-I/Users/leti/Library/Developer/Xcode/DerivedData/qsdfghj$`-douqygbrghbbyeevylooywioybsq/Build/Intermediates/qsdfghj$`.build/Debug-iphonesimulator/qsdfghj$`.build/qsdfghj$`-all-target-headers.hmap" -iquote "/Users/leti/Library/Developer/Xcode/DerivedData/qsdfghj$`-douqygbrghbbyeevylooywioybsq/Build/Intermediates/qsdfghj$`.build/Debug-iphonesimulator/qsdfghj$`.build/qsdfghj$`-project-headers.hmap" "-I/Users/leti/Library/Developer/Xcode/DerivedData/qsdfghj$`-douqygbrghbbyeevylooywioybsq/Build/Products/Debug-iphonesimulator/include" "-I/Users/leti/Library/Developer/Xcode/DerivedData/qsdfghj$`-douqygbrghbbyeevylooywioybsq/Build/Intermediates/qsdfghj$`.build/Debug-iphonesimulator/qsdfghj$`.build/DerivedSources/i386" "-I/Users/leti/Library/Developer/Xcode/DerivedData/qsdfghj$`-douqygbrghbbyeevylooywioybsq/Build/Intermediates/qsdfghj$`.build/Debug-iphonesimulator/qsdfghj$`.build/DerivedSources" "-F/Users/leti/Library/Developer/Xcode/DerivedData/qsdfghj$`-douqygbrghbbyeevylooywioybsq/Build/Products/Debug-iphonesimulator" -c "/Users/leti/Desktop/qsdfghj$`/qsdfghj$`/qsdfghj$`-Prefix.pch" -o "/Users/leti/Library/Developer/Xcode/DerivedData/qsdfghj$`-douqygbrghbbyeevylooywioybsq/Build/Intermediates/PrecompiledHeaders/qsdfghj$`-Prefix-dmcgpqormqwdhqfddykfjynaflet/qsdfghj$`-Prefix.pch.pth" -MMD -MT dependencies -MF "/Users/leti/Library/Developer/Xcode/DerivedData/qsdfghj$`-douqygbrghbbyeevylooywioybsq/Build/Intermediates/PrecompiledHeaders/qsdfghj$`-Prefix-dmcgpqormqwdhqfddykfjynaflet/qsdfghj$`-Prefix.pch.d"
error: can't exec '/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/clang' (No such file or directory)
Command /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/clang failed with exit code 71
我已卸载并重新安装Xcode，但它无效...