title: FBAccessTokenData EXC_BAD_ACCESS when refreshing access token
body: <p>I've started to receive crash logs through crashlytics after updating Facebook SDK from 3.5.3 to 3.9 in my app about an EXEC_BAD_ACCESS crash in FBAccessTokenData.m line 126</p>
  
  <p>The crash doesn't reference the part in my app where this is getting called, unfortunately, and I've been unable to reproduce it, so I can't pinpoint where exactly in my app is causing this.</p>
  
  <p>If is of any use, all crashes have been in iPhones running iOs 7.</p>
  
  <p>Crash Log:
  <img src="https://i.stack.imgur.com/2ZxYY.png" alt="crashlytics screen cap"></p>
  
  <p>line 126:</p>
  
  <pre><code>if (accessToken == nil || [accessToken stringByTrimmingCharactersInSet:
                             [NSCharacterSet whitespaceCharacterSet]].length == 0) {
  </code></pre>
  
  <p>in </p>
  
  <pre><code>+ (FBAccessTokenData *) createTokenFromString:(NSString *)accessToken
                                permissions:(NSArray *)permissions
                             expirationDate:(NSDate *)expirationDate
                                  loginType:(FBSessionLoginType)loginType
                                refreshDate:(NSDate *)refreshDate
                     permissionsRefreshDate:(NSDate *)permissionsRefreshDate
  {
  if (accessToken == nil || [accessToken stringByTrimmingCharactersInSet:
                             [NSCharacterSet whitespaceCharacterSet]].length == 0) {
      return nil;
  }
  if (expirationDate == nil) {
      expirationDate = [NSDate distantFuture];
  }
  if (refreshDate == nil) {
      refreshDate = [NSDate date];
  }
  if (permissionsRefreshDate == nil) {
      permissionsRefreshDate = [NSDate distantPast];
  }
  
  FBAccessTokenData* fbAccessToken = [[FBAccessTokenData alloc] initWithToken:accessToken
                                                                  permissions:permissions
                                                               expirationDate:expirationDate
                                                                    loginType:loginType
                                                                  refreshDate:refreshDate
                                                       permissionsRefreshDate:permissionsRefreshDate];
  return [fbAccessToken autorelease];
  }
  </code></pre>