Question

在尝试编译我编写的一个简单程序（密码）时，我收到以下错误。我知道我有一个重复的符号_OBJC_METACLASS _ $ _ Cipher，但我不确定导致这种情况发生了什么。我试着查看我是否偶然两次进口东西，但一切都很好。任何帮助深表感谢！：）

Ld "/Users/Lukas/Library/Developer/Xcode/DerivedData/Caesar_Shift-drfzwlpgygkbcifoefghycamkoya/Build/Products/Debug-iphonesimulator/Caesar Shift.app/Caesar Shift" normal i386
    cd "/Users/Lukas/Documents/Programming/iPhone Applications/Caesar Shift"
    setenv MACOSX_DEPLOYMENT_TARGET 10.6
    setenv PATH "/Developer/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin:/Developer/Applications/Xcode.app/Contents/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin"
    /Developer/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -arch i386 -isysroot /Developer/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator5.1.sdk -L/Users/Lukas/Library/Developer/Xcode/DerivedData/Caesar_Shift-drfzwlpgygkbcifoefghycamkoya/Build/Products/Debug-iphonesimulator -F/Users/Lukas/Library/Developer/Xcode/DerivedData/Caesar_Shift-drfzwlpgygkbcifoefghycamkoya/Build/Products/Debug-iphonesimulator -filelist "/Users/Lukas/Library/Developer/Xcode/DerivedData/Caesar_Shift-drfzwlpgygkbcifoefghycamkoya/Build/Intermediates/Caesar Shift.build/Debug-iphonesimulator/Caesar Shift.build/Objects-normal/i386/Caesar Shift.LinkFileList" -mmacosx-version-min=10.6 -Xlinker -objc_abi_version -Xlinker 2 -fobjc-arc -Xlinker -no_implicit_dylibs -D__IPHONE_OS_VERSION_MIN_REQUIRED=50100 -framework UIKit -framework Foundation -framework CoreGraphics -o "/Users/Lukas/Library/Developer/Xcode/DerivedData/Caesar_Shift-drfzwlpgygkbcifoefghycamkoya/Build/Products/Debug-iphonesimulator/Caesar Shift.app/Caesar Shift"

ld: duplicate symbol _OBJC_METACLASS_$_Cipher in /Users/Lukas/Library/Developer/Xcode/DerivedData/Caesar_Shift-drfzwlpgygkbcifoefghycamkoya/Build/Intermediates/Caesar Shift.build/Debug-iphonesimulator/Caesar Shift.build/Objects-normal/i386/CaesarShiftViewController.o and /Users/Lukas/Library/Developer/Xcode/DerivedData/Caesar_Shift-drfzwlpgygkbcifoefghycamkoya/Build/Intermediates/Caesar Shift.build/Debug-iphonesimulator/Caesar Shift.build/Objects-normal/i386/CaesarShiftAppDelegate.o for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Answer 1

以下是造成此错误的两个可能原因：

您已将@implementation Cipher放入头文件（可能是Cipher.h头文件）中，并且您已在CaesarShiftViewController.m和{{1}中导入了该头文件}。 CaesarShiftAppDelegate.m语句位于@implementation文件中，而不是.m文件中。
您在.h和Cipher.m中意外导入了CaesarShiftViewController.m。您应该导入CaesarShiftAppDelegate.m（注意后缀！）。

正如HachiEthan在评论中指出的那样，您可能已在Cipher.h文件中导入Cipher.m（在“支持文件”组中）。所有Caeser Shift-Prefix.pch文件都会自动导入此文件，因此它与上面的＃2具有相同的效果。

Objective-C和Xcode中的重复符号错误

1 个答案: