Undefined symbols for architecture armv7 swift

Question

I recently updated to Xcode 6 Beta 6 and now I am encountering these errors in an app that ran fine in Beta 5. I have been going through each method and commenting out the line that is causing the problem, but there has the be another solution. Here is the log.

Undefined symbols for architecture armv7:
  "__TFSs26_forceBridgeFromObjectiveCU__FTPSs9AnyObject_MQ__Q_", referenced from:
      __TFC9BookSmart32AdvanceDetailTableViewController11viewDidLoadfS0_FT_T_ in AdvanceDetailTableViewController.o
      __TFC9BookSmart32AdvanceDetailTableViewController27numberOfSectionsInTableViewfS0_FGSqCSo11UITableView_Si in AdvanceDetailTableViewController.o
      __TFC9BookSmart33AdvancesNewLocationViewController12returnedDatafS0_FCSo12NSDictionaryT_ in AdvancesNewLocationViewController.o
      __TFC9BookSmart31ArtistDetailTableViewController19scrollViewDidScrollfS0_FGSQCSo12UIScrollView_T_ in ArtistDetailTableViewController.o
      __TFC9BookSmart31ArtistDetailTableViewController14viewWillAppearfS0_FSbT_ in ArtistDetailTableViewController.o
      __TFC9BookSmart31ArtistDetailTableViewController11viewDidLoadfS0_FT_T_ in ArtistDetailTableViewController.o
      __TFC9BookSmart18ChatViewController11viewDidLoadfS0_FT_T_ in ChatViewController.o
      ...
  "__TFSs15_arrayForceCastU___FGSaQ__GSaQ0__", referenced from:
      __TFFC9BookSmart33AdvanceSectionTableViewController9tableViewFS0_FTCSo11UITableView21cellForRowAtIndexPathCSo11NSIndexPath_GSqCSo15UITableViewCell_U_FTGSQCSo21MKLocalSearchResponse_GSQCSo7NSError__T_ in AdvanceSectionTableViewController.o
      __TFFFC9BookSmart33AdvanceSectionTableViewController9tableViewFS0_FTCSo11UITableView21cellForRowAtIndexPathCSo11NSIndexPath_GSqCSo15UITableViewCell_U_FTGSQCSo21MKLocalSearchResponse_GSQCSo7NSError__T_U_FTGSQCSo13MKMapSnapshot_GSQS5___T_ in AdvanceSectionTableViewController.o
      __TFC9BookSmart32AdvanceDetailTableViewController11viewDidLoadfS0_FT_T_ in AdvanceDetailTableViewController.o
      __TFC9BookSmart32AdvanceDetailTableViewController9tableViewfS0_FTGSQCSo11UITableView_18commitEditingStyleOSC27UITableViewCellEditingStyle17forRowAtIndexPathGSQCSo11NSIndexPath__T_ in AdvanceDetailTableViewController.o
      __TFC9BookSmart32AdvanceDetailTableViewController17createAdvanceInfofS0_FTGVSs10DictionarySSSS_6forKeySS5andIdSS_T_ in AdvanceDetailTableViewController.o
      __TFC9BookSmart33AdvancesNewLocationViewController21textFieldShouldReturnfS0_FCSo11UITextFieldSb in AdvancesNewLocationViewController.o
      __TFFC9BookSmart33AdvancesNewLocationViewController21textFieldShouldReturnFS0_FCSo11UITextFieldSbU_FTGSQCSo21MKLocalSearchResponse_GSQCSo7NSError__T_ in AdvancesNewLocationViewController.o
      ...
ld: symbol(s) not found for architecture armv7
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Answer 1

There are some significant changes in Beta 6 and looks like Xcode is getting confused. A full clean didn't work either.

I've solved this and other similarly illegible errors by deleting the contents of the Derived folder. You can find where that folder is located by going to Preferences > Locations.

The default path is: /Users/[your username]/Library/Developer/Xcode/DerivedData