title: How to get an error message out of an NSError of Firebase auth login
body: <p>When i try to print the readable, userfrendly error message of firebase user login, i found i cannot use <code>NSError.localizedDiscreption</code> casue it will show "find more in details".</p>
  
  <p>And my Error message looks like this, when i use <code>print(error)</code> command</p>
  
  <pre><code>2016-05-23 21:29:33.035 Mission Board[3251:] &lt;FIRAnalytics/INFO&gt; Firebase Analytics enabled
  
  Optional(Error Domain=FIRAuthErrorDomain Code=17999 "An internal error has occurred, print and inspect the error details for more information." UserInfo={NSUnderlyingError=0x1277e2bb0 {Error Domain=FIRAuthInternalErrorDomain Code=3 "(null)" UserInfo={FIRAuthErrorUserInfoDeserializedResponseKey=&lt;CFBasicHash 0x1288eec60 [0x1a172a150]&gt;{type = immutable dict, count = 3,
  
  entries =&gt;
  
      0 : &lt;CFString 0x12890ad60 [0x1a172a150]&gt;{contents = "message"} = &lt;CFString 0x1288eec20 [0x1a172a150]&gt;{contents = "INVALID_EMAIL"}
  
      1 : errors = &lt;CFArray 0x12890ad20 [0x1a172a150]&gt;{type = immutable, count = 1, values = (
  
      0 : &lt;CFBasicHash 0x12890c660 [0x1a172a150]&gt;{type = immutable dict, count = 3,
  
  entries =&gt;
  
      0 : reason = invalid
  
      1 : message = &lt;CFString 0x128872790 [0x1a172a150]&gt;{contents = "INVALID_EMAIL"}
  
      2 : domain = global
  
  }
  
  
  
  )}
  
      2 : code = &lt;CFNumber 0xb000000000001903 [0x1a172a150]&gt;{value = +400, type = kCFNumberSInt64Type}
  
  }
  
  }}, error_name=ERROR_INTERNAL_ERROR, NSLocalizedDescription=An internal error has occurred, print and inspect the error details for more information.})
  </code></pre>
  
  <p>which is not very readable but i found in entries 1 code 0, there is a message with content "INVALID EMAIL"</p>
  
  <p>Can i just output that part to the alert to user?</p>
  
  <p>is there any built in function can do that?</p>