Xcode build failure Undefined symbols for architecture x86 64

Question

An Xcode beginner s question   It is my first experience with Xcode 4 6 3   I am trying to write a very simple console program  that searches for paired BT devices and prints them to an NSLog   It builds with the following error   Undefined symbols for architecture x86 64      OBJC CLASS   IOBluetoothDevice   referenced from        objc-class-ref in main o ld  symbol s  not found for architecture x86 64 clang  error  linker command failed with exit code 1  use -v to see invocation    I searched like crazy  The common problem should be a reference to a file  of which only the header files are imported and no implementation    m-file  is found by the linker  The IOBluetooth library is however  a standard Framework like the Foundation Framework   What am I missing in my above statement   I also have tried building it for a 32-bit machine  build fails again   It is clearly a linker error  however I have no idea  to what it relates  except that there is an issue with finding the implementation for IOBluetoothDevice  on both x86 and x64 architecture  while the header files are from a standard included Framework  called IOBluetooth   For your information my main code  main m  being    import  lt Foundation Foundation h gt   import  lt IOBluetooth objc IOBluetoothDevice h gt              Note the import for bluetooth  import  lt IOBluetooth objc IOBluetoothDeviceInquiry h gt       Note the import for bluetooth   int main int argc  const char   argv           autoreleasepool           IOBluetoothDevice  currentDevice          NSArray  devices     IOBluetoothDevice pairedDevices             for  id currentDevice in devices             NSLog    i         currentDevice classOfDevice      currentDevice name                             return 0      Thanks for any help or pointers to the right direction

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In my case  I built a custom framework with Deployment target set to 9 1  but the Deployment target of my app was lower  which supports 8 1  Minimize the custom framework  Deployment target solved my problem

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I had the same error  because instead of deleting a file I simply removed references to it  Locating the file in Finder and removing it helped

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I tried just about everything here but my problem turned out to be the remnants of a previous cocoapods build   What worked for me was    rm -Rf Pods  pod install  Delete Derived Data  Window Projects    select your target  click Delete Button  Rebuild

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Could also be an  include  lt windows h gt  in the  c file that you re trying to compile

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UPD  Apple requires to use arm64 architecture  Do not use x32 libraries in your project  So the answer below is not correct anymore     Old answer  The new Xcode 5 1 sets the architecture armv7 armv7s and arm64 as default   And sometimes the error  build failure    Undefined symbols for architecture x86 64     may be caused by this  Because  some libs  not Apple s  were compiled for x32 originally and doesn t support x64   So what you need  is to change the  Architectures  for your project target like this  NB  If you re using Cocoapods - you should do the same for  Pods  target

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It looks like you are missing including the IOBluetooth framework in your project  You can add it by   Clicking on your project in the upper left of the left pane  the blue icon    In the middle pane  click on the Build Phases tab   Under  quot Link Binary With Libraries quot   click on the plus button   Find the IOBluetooth framework from the list and hit Add      This will make sure that the IOBluetooth framework definitions are found by the linker  You can see that the framework is a member of your target by clicking on the framework in the left pane and seeing the framework s target membership in the right pane  note I ve moved the framework under the Frameworks group for organization purposes

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I got it solved by adding  -lc    in Other Linker Flags in Build Settings

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I know it s an old question but today got the same error and non of the above solutions worked   Have fixed it however by setting option   Project - gt  Architecture - gt  Build Active Architecture Only   to Yes  and project compiles and builds properly

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I have found this can also occur if you drag a folder with Objective-C files into your project  If that folder appears blue I think it indicates its not properly linked  You can verify this  if you use version control  because whenever you add new files the pbxproj file should update with links to those new files  However you may find that after you added a folder that the pbxproj file did not change  and hence there is a linking error   So you will get auto-complete working and it will find the classes you imported  but when it goes to actually build the image it fails with this error code   The solution is to not add the folder but rather add the files  Do this and you should see the pbxproj file update and it should fix this error   This also assumes you ve done what was suggested above and have properly linked all the right frameworks

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I have also seen this error on Xcode 7 2 when the derived data becomes corrupted  in my case I interrupted a build and suspect that was the root cause    So if the other solutions  notably Chris s and BraveS s which I suspect are more likely  do not fit your problem try deleting derived data  Select  Window   Projects   Derived Data -  Delete  and re-building    Added for reference by others - I know the original question has been answered correctly

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I also encountered the same problem   the above methods will not work   I accidentally deleted the files in the following directory on it     Or    Library Developer Xcode DerivedData

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When updating to Xcode 7 1  you might see this type of error  and it can t be resolved by any of the above answers   One of the symptoms in my case was that the app runs on the device not in the simulator   You ll probably see a huge number of errors related to pretty much all of the frameworks you re using   The fix is actually quite simple   You just need to delete an entry from the  Framework Search Paths  setting  found in your TARGETS   Build Settings   Search Paths section  make sure the  All  tab is selected     If you see another entry here  besides   inherited   for your main target s  or your test target  just delete the faulty path from all targets and rebuild

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in my case  removing selection of target membership and then select again fix the issue    Check William Cerniuk answer with the attachment photo

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In my case problem was compiled framework architecture  I m running Xcode 11 and using Swift 5 1   I had 3 target like      MyApp   MyAppTests MyAppFrameWork    I was tried to run tests but MyAppFrameWork product was compiled for Generic iOS Devices and the Test target needed an arm x86-64  So I rebuilt Framework for iOS Simulators and test cases successfuly start running

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Finally  got the project compiled in Xcode with a clean build  I have to run this first  rm -rf   Library Developer Xcode DerivedData    Then the building is ok  ref

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Undefined symbols for architecture x86 64      OBJC CLASS   xxx     referenced from          objc-class-ref in yyy o   This generally means  you are calling  xxx   it may be a framework or class  from the class  yyy   The compiler can not locate the  xxx  so this error occurs    You need to add the missing files in this case  xxx   by right click on your project folder in navigator window and tap on  Add files to  YourProjectName   option    A popup window will open your project files in Finder  There  you can see the missing files and just add them to your project  Don t forget to check the  Copy items if needed  box  Good luck

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Sometime  I forget to copy library from Release-universal and mistakenly copy from Release-iphoneos  Usually Release-iphoneos contains  a file which has been pruned for X86  and so it gives the error

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In my Case   it was not a library  it was some classes         Undefined symbols for architecture x86 64      OBJC CLASS   ClassNmae   referenced from  objc-class-ref in   SomeClassName              d  symbol s  not found for architecture x86 64      clang  error  linker command failed with exit code 1  use -v to see   invocation    Solution  I had several targets in Xcode with several schemas   Production   Dev etc      some of my newly added implementation   Class m   were missing in      Xcode- Targets- Build Phases- Compile Sources   So I had to add them manually    then I could compile  amp  build successfully

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If you re getting this error when trying to link to a C file  first double check the function names for typos   Next double check that you are not trying to call a C function from a C     Objective-C   environment without using the extern C    construct   I was tearing my hair out because I had a class that was in a  mm file which was trying to call C functions   It doesn t work because in C    the symbols are mangled   You can actually see the concrete symbols generated using the nm tool   Terminal to the path of the  o files  and run nm -g on the file that is calling the symbol and the one that should have the symbol  and you should see if they match up or not  which can provide clues for the error   nm -g file o   You can inspect the C   symbols demangled with this   nm -gC file o

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I have faced this issue many times  This usually comes when you delete your build folder   The easy solution is to de-integrate and install the pod files again   pod deintegrate pod install

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For me  this started to happen after merge conflict   I tried to clean and remove build folder  but none of it helped  This issue kept happening regardless  Then I relinked the reference by deleting the groups that was problematic and re-added to the project and it worked

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This might help somebody  It took me days to finally figure it out  I am working in OBJ-C and I went to    Project -  Build Phases -  Compile sources and added the new VC m file I had just added     I am working with legacy code and I am usually a swifty  new to OBJ-C so I didn t even think to import my  m files into a sources library    EDIT   Ran into this problem a second time and it was something else  This answer saved me after 5 hours of debugging  Tried all of the options on this thread and more  https   stackoverflow com a 13625967 7842175 Please give him credit if this helps you  but basically you might need to set your file to its target in file inspector      All in all  this is a very vague Error code that could be caused for a lot of reasons  so keep on trying different options

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in my case I had to add       target  SomeTargetTests  do         inherit   search paths     end  to my podfile and then delete the  Pods directory and run  pod install    Xcode 10 1

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I am late to the party but thought of sharing one more scenario where this could happen  I was working on a framework and was distributing it over cocoapods  The framework had both objective c and swift classes and protocols and it was building successfully  While using pod in another framework or project it was giving this error as I forgot to include  m files in podspec  Please include  swtift  h and  m files in your podspec sources as below  s source files    Projectname Projectname       swift h m    I hope it saves someone else s time

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Under Xcode 9 0b5 you may encounter this because Xcode 9 0b5 has a bug in it where when you add source code  it does not honor the target settings  You must go in and set each file s target manually afterwords

[objective-c] Xcode build failure "Undefined symbols for architecture x86_64"

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