title: Undefined symbols for architecture x86_64 - ld: symbol(s) not found for architecture x86_64
body: <p>I am not able to solve the below error. I have used cocoapods
   for external libs/frameworks.</p>
  
  <pre><code>Ld /Users/MyAppapp/Library/Developer/Xcode/DerivedData/MyApp-ceyvfirzookxqtdglefjjtyixokw/Build/Products/Debug-iphonesimulator/MyApp.app/MyApp normal x86_64
      cd /Users/MyAppapp/Documents/MyApp-ios
      export IPHONEOS_DEPLOYMENT_TARGET=7.0
      export PATH="/Applications/Xcode 2.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin:/Applications/Xcode 2.app/Contents/Developer/usr/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin"
      /Applications/Xcode\ 2.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -arch x86_64 -isysroot /Applications/Xcode\ 2.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator9.0.sdk -L/Users/MyAppapp/Library/Developer/Xcode/DerivedData/MyApp-ceyvfirzookxqtdglefjjtyixokw/Build/Products/Debug-iphonesimulator -L/Users/MyAppapp/Documents/MyApp-ios/Pods/Realm/core -F/Users/MyAppapp/Library/Developer/Xcode/DerivedData/MyApp-ceyvfirzookxqtdglefjjtyixokw/Build/Products/Debug-iphonesimulator -F/Users/MyAppapp/Documents/MyApp-ios/Pods/Crashlytics -F/Users/MyAppapp/Documents/MyApp-ios/Pods/Digits -F/Users/MyAppapp/Documents/MyApp-ios/Pods/Fabric -F/Users/MyAppapp/Documents/MyApp-ios/Pods/TwitterCore -F/Users/MyAppapp/Documents/MyApp-ios/Pods/TwitterKit -F/Users/MyAppapp/Documents/MyApp-ios -F/Users/MyAppapp/Documents/MyApp-ios/MyApp/Frameworks -F/Users/MyAppapp/Documents/MyApp-ios/MyApp/Frameworks/FacebookSDK -filelist /Users/MyAppapp/Library/Developer/Xcode/DerivedData/MyApp-ceyvfirzookxqtdglefjjtyixokw/Build/Intermediates/MyApp.build/Debug-iphonesimulator/MyApp.build/Objects-normal/x86_64/MyApp.LinkFileList -Xlinker -rpath -Xlinker @executable_path/Frameworks -mios-simulator-version-min=7.0 -Xlinker -objc_abi_version -Xlinker 2 -ObjC -ObjC -lBolts -lDiskcached -lFBSDKCoreKit -lFBSDKLoginKit -lFBSDKShareKit -lImageLoader -lMBProgressHUD -lRealm -lc++ -lrealm-ios -lz -framework Accounts -framework AddressBook -framework CoreData -framework CoreGraphics -framework CoreText -framework Crashlytics -framework DigitsKit -framework Fabric -framework Foundation -framework QuartzCore -framework Security -framework Social -framework SystemConfiguration -framework TwitterCore -framework TwitterKit -framework UIKit -weak_framework Accounts -weak_framework AudioToolbox -weak_framework CoreGraphics -weak_framework CoreLocation -weak_framework Foundation -weak_framework QuartzCore -weak_framework Security -weak_framework Social -weak_framework UIKit -fobjc-arc -fobjc-link-runtime /Users/MyAppapp/Library/Developer/Xcode/DerivedData/MyApp-ceyvfirzookxqtdglefjjtyixokw/Build/Products/Debug-iphonesimulator/libMBProgressHUD.a -framework SystemConfiguration -framework QuartzCore -framework OpenGLES -lz -licucore -lc++ -framework ImageIO -framework GLKit -framework CoreText -framework CoreLocation -framework CoreData -framework AVFoundation -framework CoreGraphics -framework UIKit -framework Foundation -lPods -Xlinker -dependency_info -Xlinker /Users/MyAppapp/Library/Developer/Xcode/DerivedData/MyApp-ceyvfirzookxqtdglefjjtyixokw/Build/Intermediates/MyApp.build/Debug-iphonesimulator/MyApp.build/Objects-normal/x86_64/MyApp_dependency_info.dat -o /Users/MyAppapp/Library/Developer/Xcode/DerivedData/MyApp-ceyvfirzookxqtdglefjjtyixokw/Build/Products/Debug-iphonesimulator/MyApp.app/MyApp
  
  ld: warning: directory not found for option '-F/Users/MyAppapp/Documents/MyApp-ios/MyApp/Frameworks'
  ld: warning: directory not found for option '-F/Users/MyAppapp/Documents/MyApp-ios/MyApp/Frameworks/FacebookSDK'
  Undefined symbols for architecture x86_64:
    "_OBJC_CLASS_$_TWTRAPIResponseValidator", referenced from:
        objc-class-ref in DigitsKit(DGTNetworkingHelper.o)
    "_OBJC_CLASS_$_TWTRGuestSessionRefreshStrategy", referenced from:
        objc-class-ref in DigitsKit(Digits.o)
    "_OBJC_CLASS_$_TWTRNetworkingPipeline", referenced from:
        objc-class-ref in DigitsKit(DGTNetworkingHelper.o)
    "_OBJC_CLASS_$_TWTRSessionStore", referenced from:
        objc-class-ref in DigitsKit(Digits.o)
    "_OBJC_CLASS_$_TWTRURLSessionDelegate", referenced from:
        objc-class-ref in DigitsKit(DGTNetworkingHelper.o)
  ld: symbol(s) not found for architecture x86_64
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  </code></pre>
  
  <p>Searched and tried many solution like - Linker error, verifying build setting OR framework missing from project directory, Changing valid architecture in build setting, cleaning up derived data but couldn't solve the issue.</p>
  
  <p>In some post I saw missing <code>#inclue</code> or <code>#import</code> but in below errors I am not getting where. Any suggestion.</p>