title: Xcode 6 linker error - Undefined symbols for architecture armv7
body: <p>After upgrading to Xcode 6 beta 7 (and now still with Xcode 6 GM) I am unable to link my Swift app. I receive errors such as:</p>
  
  <blockquote>
    <p>Undefined symbols for architecture armv7:
      "_swift_stdlib_compareNSStringDeterministicUnicodeCollation", referenced from:</p>
    
    <p>...</p>
    
    <p>ld: symbol(s) not found for architecture armv7
    clang: error: linker command failed with exit code 1 (use -v to see invocation)</p>
  </blockquote>
  
  <p>I have seen the other SO posts that recommend deleting the Derived Data folder and/or using the Clean Build Folder option to get past this error, but that solution didn't help at all in my case. Nothing has changed about my code or the CocoaPods I'm using since Xcode 6 beta 5 which is the last time it worked.</p>
  
  <p>Any ideas?</p>
  
  <p>EDIT:</p>
  
  <p>A full posting of the error log:</p>
  
  <blockquote>
    <p>Undefined symbols for architecture arm64:
      "_swift_stdlib_compareNSStringDeterministicUnicodeCollation", referenced from:
          <strong>TFC12MyProject21BarcodeViewController13captureOutputfS0_FTGSQCSo15AVCaptureOutput_24didOutputMetadataObjectsGSQGSaPSs9AnyObject___14fromConnectionGSQCSo19AVCaptureConnection__T_ in BarcodeViewController.o
      "__TFSs21_arrayConditionalCastU___FGSaQ__GSqGSaQ0_</strong>", referenced from:
          <strong>TFC12MyProject27SessionsTableViewController17viewWillDisappearfS0_FSbT_ in SessionsTableViewController.o
      "__TFSs15_arrayForceCastU___FGSaQ__GSaQ0</strong>", referenced from:
          __TFC12MyProject7RestApi12tokenMappingfS0_FT_CSo15RKEntityMapping in RestApi.o
          __TFC12MyProject28AttendeesTableViewControllerg24fetchedResultsControllerCSo26NSFetchedResultsController in AttendeesTableViewController.o
          __TFC12MyProject27SessionsTableViewControllerg24fetchedResultsControllerCSo26NSFetchedResultsController in SessionsTableViewController.o
          __TFC12MyProject21BarcodeViewController13startScanningfS0_FT_Sb in BarcodeViewController.o
      "__TFSs26_forceBridgeFromObjectiveCU__FTPSs9AnyObject_MQ__Q_", referenced from:
          __TFC12MyProject7RestApi12resetRestKitfS0_FT_T_ in RestApi.o
          __TFC12MyProject16BluetoothManager17_startAdvertisingfS0_FT_T_ in BluetoothManager.o
          __TFC12MyProject19LoginViewController32registerForKeyboardNotificationsfS0_FT_T_ in LoginViewController.o
          __TFC12MyProject19LoginViewController35deregisterFromKeyboardNotificationsfS0_FT_T_ in LoginViewController.o
          __TFC12MyProject19LoginViewController16callProcessLoginfS0_FT_T_ in LoginViewController.o
          __TFC12MyProject21CheckinViewController16enableBeaconModefS0_FT_T_ in CheckinViewController.o
          __TFC12MyProject21BarcodeViewController13startScanningfS0_FT_Sb in BarcodeViewController.o
          ...
    ld: symbol(s) not found for architecture arm64
    clang: error: linker command failed with exit code 1 (use -v to see invocation)</p>
  </blockquote>