嗨，我已经有很长一段时间遇到这个问题了，它让我疯了。
Ld /Users/soc/Library/Developer/Xcode/DerivedData/friendSpotted-dohwbjpnqfiztkcphlehsjqjusjk/Build/Products/Debug-iphonesimulator/friendSpotted.app/friendSpotted normal i386
cd /Users/soc/Desktop/friendSpotted
setenv MACOSX_DEPLOYMENT_TARGET 10.6
setenv PATH "/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin:/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin"
/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/clang -arch i386 -isysroot /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator5.0.sdk -L/Users/soc/Library/Developer/Xcode/DerivedData/friendSpotted-dohwbjpnqfiztkcphlehsjqjusjk/Build/Products/Debug-iphonesimulator -F/Users/soc/Library/Developer/Xcode/DerivedData/friendSpotted-dohwbjpnqfiztkcphlehsjqjusjk/Build/Products/Debug-iphonesimulator -filelist /Users/soc/Library/Developer/Xcode/DerivedData/friendSpotted-dohwbjpnqfiztkcphlehsjqjusjk/Build/Intermediates/friendSpotted.build/Debug-iphonesimulator/friendSpotted.build/Objects-normal/i386/friendSpotted.LinkFileList -mmacosx-version-min=10.6 -Xlinker -objc_abi_version -Xlinker 2 -Xlinker -no_implicit_dylibs -D__IPHONE_OS_VERSION_MIN_REQUIRED=50000 -framework MobileCoreServices -framework UIKit -framework Foundation -framework CoreGraphics -o /Users/soc/Library/Developer/Xcode/DerivedData/friendSpotted-dohwbjpnqfiztkcphlehsjqjusjk/Build/Products/Debug-iphonesimulator/friendSpotted.app/friendSpotted
Undefined symbols for architecture i386:
"_OBJC_CLASS_$_ViewController", referenced from:
objc-class-ref in AppDelegate.o
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)
这实际上让我走到了尽头，我在这个网站上尝试了一些解决方案无济于事。我已经检查了viewController.m以查看它是否针对正确的项目，并且据我所知，我已经添加了所有正确的框架。见下文：
请真的需要帮助，我将非常感激。