我强烈建议你不要因为我的经验大多数用户这样做不会通过您的应用程序而不是FB应用程序或浏览器登录Facebook。他们只是不信任第三方应用。

I strongly recommend you not to do that cause from my experience most users won't login to Facebook via your app instead of FB application or browser. They just don't trust third party apps.

编辑：

但如果你仍然不想使用需要更改的浏览器/ FBApplication：

But if you still do not want to use browser/FBApplication you need to change:

- (void)authorize:(NSArray *)permissions
         delegate:(id<FBSessionDelegate>)delegate
       localAppId:(NSString *)localAppId {
  self.localAppId = localAppId;
  self.permissions = permissions;

  _sessionDelegate = delegate;

  [self authorizeWithFBAppAuth:YES safariAuth:YES];
}

Facebook.m of FBConnect框架中的NO

to NO in Facebook.m of FBConnect framework