Facebook iOS SDK 3.1.1：如何检查过期的令牌？

Question

How do I check if the access token is expired via the iOS SDK?

I call [FBSession openActiveSessionWithReadPermissions:permissions allowLoginUI:NO completionHandler:nil] when my app starts to load the session from the cache.

Active session then looks like this:

<FBSession: 0x1fdcbae0,
state: FBSessionStateOpen,
loginHandler: 0x0,
appID: 1234567890,
urlSchemeSuffix: ,
tokenCachingStrategy:<FBSessionTokenCachingStrategy: 0x1fdcb840>, 
expirationDate: 4001-01-01 00:00:00 +0000,
refreshDate: 2012-12-10 07:09:18 +0000,
attemptedRefreshDate: 0001-12-30 00:00:00 +0000,
permissions:(
    email
)

FBSession.activeSession.isOpen always returns YES. Why is expirationDate in the distant future?

On my server I call a method via PHP, and I'm told the session has expired. How should I handle this?

Answer 1

The best way to check for an expired token is to actually try an API call and handle errors. For example, after your open call you can call startForMeWithCompletionHandler: in the completion handler. In the startForMeWithCompletionHandler: completion handler you can check error.

See this doc for more info on how you can handle the errors you may get back: https://developers.facebook.com/docs/reference/api/errors/