title: Touch ID build error on Xcode6-beta5 running on real device iphone5s
body: <p>I am using Xcode6-beta5 to integrate touch ID authentication into my own application.Running on real device iphone5s(iOS8-beta5), using the following code.
  Already #import .</p>
  
  <pre><code>LAContext *myContext = [[LAContext alloc] init];
  NSError *authError = nil;
  NSString *myLocalizedReasonString = @"use touch id to unlock app";
  
  if ([myContext canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&amp;authError]) {
       [myContext evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics
                 localizedReason:myLocalizedReasonString
                           reply:^(BOOL success, NSError *error) {
                              if (success) {
                                 UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"success" message:@"pass auth" delegate:self cancelButtonTitle:NSLocalizedString(@"OK", @"OK button") otherButtonTitles:nil];
  
                                 [alert show];
                                 [alert release];
  
                                 // User authenticated successfully, take appropriate action
                              } else {
                                 UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"fail" message:@"fail auth" delegate:self cancelButtonTitle:NSLocalizedString(@"OK", @"OK button") otherButtonTitles:nil];
  
                                 [alert show];
                                 [alert release];
                                 // User did not authenticate successfully, look at error and take appropriate action
                              }
                           }];
    } else {
       // Could not evaluate policy; look at authError and present an appropriate message to user
    }
  </code></pre>
  
  <p>But when I compile and run it shows build failed:</p>
  
  <p><i>
  Ld build/HWC.build/Debug-iphoneos/HWC.build/Objects-normal/armv7/HWC normal armv7
      cd /Users/i307466/Downloads/OneBridge/trunk/Apps/iPhone/WorkFlow
      export IPHONEOS_DEPLOYMENT_TARGET=8.0
      export PATH="/Applications/Xcode6-Beta5.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin:/Applications/Xcode6-Beta5.app/Contents/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin"
      /Applications/Xcode6-Beta5.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -arch armv7 -isysroot /Applications/Xcode6-Beta5.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS8.0.sdk -L/Users/i307466/Downloads/OneBridge/trunk/Apps/iPhone/WorkFlow/build/Debug-iphoneos -F/Users/i307466/Downloads/OneBridge/trunk/Apps/iPhone/WorkFlow/build/Debug-iphoneos -filelist /Users/i307466/Downloads/OneBridge/trunk/Apps/iPhone/WorkFlow/build/HWC.build/Debug-iphoneos/HWC.build/Objects-normal/armv7/HWC.LinkFileList -Xlinker -map -Xlinker /Users/i307466/Downloads/OneBridge/trunk/Apps/iPhone/WorkFlow/build/HWC.build/Debug-iphoneos/HWC.build/HWC-LinkMap-normal-armv7.txt -dead_strip -all_load ../../../Pioneer/MOClients/iPhone/build/Debug-iphoneos/libMO.a ../../../Pioneer/Robie/Device/iPhone/Datavault/build/Debug-iphoneos/libDatavault.a ../../../TPTools/iOS/afaria/libs/Debug-iphoneos/libAfariaSLL.a ../../../TPTools/PhoneGap/iOS/CordovaLib/build/Debug-iphoneos/libCordova.a ../../../TPTools/iOS/ClientUtil/Libraries/Debug-iphoneos/libsupClientUtil.a ../../../TPTools/iOS/ClientUtil/Libraries/Debug-iphoneos/libSUPSupportability.a ../../../TPTools/iOS/ClientUtil/Libraries/Debug-iphoneos/libPerformanceLib.a ../../../Pioneer/Robie/Device/iPhone/Widgets/HWCLib/build/Debug-iphoneos/libHWC.a ../../../TPTools/OpenSSL/iOS/Debug-iphoneos/libcrypto.a -fobjc-link-runtime -miphoneos-version-min=8.0 -lstdc++.6.0.9 -framework CoreTelephony -lz.1.2.5 -lstdc++ -framework CoreGraphics -framework CFNetwork -framework Foundation -framework MobileCoreServices -framework QuartzCore -framework Security -framework UIKit -licucore.A -framework AddressBook -framework CoreMedia -framework AudioToolbox -framework AVFoundation -framework CoreLocation -framework AddressBookUI -framework SystemConfiguration -Xlinker -dependency_info -Xlinker /Users/i307466/Downloads/OneBridge/trunk/Apps/iPhone/WorkFlow/build/HWC.build/Debug-iphoneos/HWC.build/Objects-normal/armv7/HWC_dependency_info.dat -o /Users/i307466/Downloads/OneBridge/trunk/Apps/iPhone/WorkFlow/build/HWC.build/Debug-iphoneos/HWC.build/Objects-normal/armv7/HWC</p>
  
  <p>Undefined symbols for architecture armv7:
    "_OBJC_CLASS_$_LAContext", referenced from:
        objc-class-ref in HWCAppDelegate.o
  ld: symbol(s) not found for architecture armv7
  clang: error: linker command failed with exit code 1 (use -v to see invocation)</p>
  
  <p>Ld build/HWC.build/Debug-iphoneos/HWC.build/Objects-normal/arm64/HWC normal arm64
      cd /Users/i307466/Downloads/OneBridge/trunk/Apps/iPhone/WorkFlow
      export IPHONEOS_DEPLOYMENT_TARGET=8.0
      export PATH="/Applications/Xcode6-Beta5.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin:/Applications/Xcode6-Beta5.app/Contents/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin"
      /Applications/Xcode6-Beta5.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -arch arm64 -isysroot /Applications/Xcode6-Beta5.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS8.0.sdk -L/Users/i307466/Downloads/OneBridge/trunk/Apps/iPhone/WorkFlow/build/Debug-iphoneos -F/Users/i307466/Downloads/OneBridge/trunk/Apps/iPhone/WorkFlow/build/Debug-iphoneos -filelist /Users/i307466/Downloads/OneBridge/trunk/Apps/iPhone/WorkFlow/build/HWC.build/Debug-iphoneos/HWC.build/Objects-normal/arm64/HWC.LinkFileList -Xlinker -map -Xlinker /Users/i307466/Downloads/OneBridge/trunk/Apps/iPhone/WorkFlow/build/HWC.build/Debug-iphoneos/HWC.build/HWC-LinkMap-normal-arm64.txt -dead_strip -all_load ../../../Pioneer/MOClients/iPhone/build/Debug-iphoneos/libMO.a ../../../Pioneer/Robie/Device/iPhone/Datavault/build/Debug-iphoneos/libDatavault.a ../../../TPTools/iOS/afaria/libs/Debug-iphoneos/libAfariaSLL.a ../../../TPTools/PhoneGap/iOS/CordovaLib/build/Debug-iphoneos/libCordova.a ../../../TPTools/iOS/ClientUtil/Libraries/Debug-iphoneos/libsupClientUtil.a ../../../TPTools/iOS/ClientUtil/Libraries/Debug-iphoneos/libSUPSupportability.a ../../../TPTools/iOS/ClientUtil/Libraries/Debug-iphoneos/libPerformanceLib.a ../../../Pioneer/Robie/Device/iPhone/Widgets/HWCLib/build/Debug-iphoneos/libHWC.a ../../../TPTools/OpenSSL/iOS/Debug-iphoneos/libcrypto.a -fobjc-link-runtime -miphoneos-version-min=8.0 -lstdc++.6.0.9 -framework CoreTelephony -lz.1.2.5 -lstdc++ -framework CoreGraphics -framework CFNetwork -framework Foundation -framework MobileCoreServices -framework QuartzCore -framework Security -framework UIKit -licucore.A -framework AddressBook -framework CoreMedia -framework AudioToolbox -framework AVFoundation -framework CoreLocation -framework AddressBookUI -framework SystemConfiguration -Xlinker -dependency_info -Xlinker /Users/i307466/Downloads/OneBridge/trunk/Apps/iPhone/WorkFlow/build/HWC.build/Debug-iphoneos/HWC.build/Objects-normal/arm64/HWC_dependency_info.dat -o /Users/i307466/Downloads/OneBridge/trunk/Apps/iPhone/WorkFlow/build/HWC.build/Debug-iphoneos/HWC.build/Objects-normal/arm64/HWC</p>
  
  <p>Undefined symbols for architecture arm64:
    "_OBJC_CLASS_$_LAContext", referenced from:
        objc-class-ref in HWCAppDelegate.o
  ld: symbol(s) not found for architecture arm64
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  </i></p>