CODEWITHSUNDEEP
objective-c
user1563777
user1563777

Reputation: 21

duplicate symbol error in Objective-C and Xcode

I am getting the following error when trying to compile a simple program I wrote (a cipher). I understand that I have a duplicate symbol _OBJC_METACLASS_$_Cipher, but I am unsure of what is happening to cause this. I tried to check to see if I accidentally imported stuff twice, but all was good. Any help is much appreciated! :)

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)

Upvotes: 1

Views: 1007

Answers (1)

rob mayoff
rob mayoff

Reputation: 385600

Here are two likely reasons for this error:

  1. You have put @implementation Cipher in a header file (probably the Cipher.h header file), and you've imported that header file in both CaesarShiftViewController.m and CaesarShiftAppDelegate.m. An @implementation statement goes in a .m file, not a .h file.

  2. You have accidentally imported Cipher.m in both CaesarShiftViewController.m and CaesarShiftAppDelegate.m. You were supposed to import Cipher.h (notice the suffix!).

As HachiEthan pointed out in a comment, you might have imported Cipher.m in your Caeser Shift-Prefix.pch file (in the “Supporting Files” group). This file is automatically imported by all .m files, so it would have the same effect as my #2 above.

Upvotes: 4

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