SWIFT Apple Mach-O Linker "_OBJC_CLASS _ $ _ BFExectur" error

Trying to use Parse with X code and target C. 4 different errors appear. Suggestions?

Undefined symbols for architecture x86_64:
  "_OBJC_CLASS_$_BFExecutor", referenced from:
    objc-class-ref in Parse(BFTask+Private.o)
    l_OBJC_$_CATEGORY_BFExecutor_$_Background in Parse(BFTask+Private.o)
  "_OBJC_CLASS_$_BFTask", referenced from:
    objc-class-ref in Parse(PSObject.o)
    objc-class-ref in Parse(PFFile.o)
    objc-class-ref in Parse(PFNetworkCommandRunner.o)
    objc-class-ref in Parse(PFQuery.o)
    objc-class-ref in Parse(PFRetryingCommandRunner.o)
    objc-class-ref in Parse(PFTaskQueue.o)
    objc-class-ref in Parse(PFUser.o)
    ...
  "_OBJC_CLASS_$_BFTaskCompletionSource", referenced from:
    objc-class-ref in Parse(PFObject.o)
    objc-class-ref in Parse(PFCommandCache.o)
    objc-class-ref in Parse(PFFile.o)
    objc-class-ref in Parse(PFNetworkCommandRunner.o)
    objc-class-ref in Parse(BFTask+Private.o)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)