1. 对 graph.facebook.com/me 的调用只会在您有效的情况下返回结果身份验证令牌。如果没有访问令牌，您也不会登录。


2. 请求 offline_access 权限或者不要使用新的登录机制但是登录对话框。该对话框将弹出您的应用程序，只询问一次权限。

1. A call to graph.facebook.com/me will return results only in case you have valid auth token. Without an access token you are not logged in, too.
2. Either request offline_access privilege or just do not use the new login mechanism but a login dialog. The dialog will popover your app and only ask once for privileges.

我目前在iPhone上，因此无法提供代码，在SDK中寻找FBDialog方法。

I'm currently on iPhone, so can not provide code, but have look for the FBDialog methods in SDK.