title: Undefined symbols for architecture i386 when trying to compile AFNetworking 2.0
body: <p>I added AFNetworking 2.0 to my project.
  I did it without the use CocoaPods - I just added the files to the project, making sure to copy the files to target.</p>
  
  <p>When I try to compile the project I get the following error:</p>
  
  <pre><code>Undefined symbols for architecture i386:
    "_SecCertificateCopyData", referenced from:
        _AFCertificateTrustChainForServerTrust in AFSecurityPolicy.o
    "_SecCertificateCreateWithData", referenced from:
        _AFPublicKeyForCertificate in AFSecurityPolicy.o
    "_SecPolicyCreateBasicX509", referenced from:
        _AFPublicKeyForCertificate in AFSecurityPolicy.o
        _AFPublicKeyTrustChainForServerTrust in AFSecurityPolicy.o
    "_SecTrustCopyPublicKey", referenced from:
        _AFPublicKeyForCertificate in AFSecurityPolicy.o
        _AFPublicKeyTrustChainForServerTrust in AFSecurityPolicy.o
    "_SecTrustCreateWithCertificates", referenced from:
        _AFPublicKeyForCertificate in AFSecurityPolicy.o
        _AFPublicKeyTrustChainForServerTrust in AFSecurityPolicy.o
    "_SecTrustEvaluate", referenced from:
        _AFPublicKeyForCertificate in AFSecurityPolicy.o
        _AFServerTrustIsValid in AFSecurityPolicy.o
        _AFPublicKeyTrustChainForServerTrust in AFSecurityPolicy.o
    "_SecTrustGetCertificateAtIndex", referenced from:
        _AFCertificateTrustChainForServerTrust in AFSecurityPolicy.o
        _AFPublicKeyTrustChainForServerTrust in AFSecurityPolicy.o
    "_SecTrustGetCertificateCount", referenced from:
        _AFCertificateTrustChainForServerTrust in AFSecurityPolicy.o
        _AFPublicKeyTrustChainForServerTrust in AFSecurityPolicy.o
  ld: symbol(s) not found for architecture i386
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  </code></pre>
  
  <p>What is wrong with my project?</p>