facebook - FBSessionState 常量的问题

Question

我正在开发一个使用 Facebook 登录和分享的 iOS 应用。这需要检查各个地方的活动会话状态。

Facebook 提供的代码检查当前状态并决定是否打开一个新会话。然而，记录会话状态表明它可能是打开的，即使与 FBSessionState 常量的比较可能表明它已关闭。

例如，使用以下代码（facebook 的），即使我的会话状态记录为 1，它也不等于 FBSessionStateOpen 或 FBSessionStateOpenTokenExtended，并打开了一个新会话。

NSLog(@"facebook session state: %lu", FBSession.activeSession.state);
// log shows 1

if (FBSession.activeSession.state == FBSessionStateOpen
    || FBSession.activeSession.state == FBSessionStateOpenTokenExtended) {

    NSLog(@"facebook session already open");
    // do stuff...

} else {
    // new session opened anyway
    NSLog(@"open new facebook session");
    /* code to open a session omitted here
    ...
    */
}

尽管常量定义显示1 = FBSessionStateOpen。

FBSession.h：

typedef NS_ENUM(NSUInteger, FBSessionState) {
/*! One of two initial states indicating that no valid cached token was found */
FBSessionStateCreated                   = 0,
/*! One of two initial session states indicating that a cached token was loaded;
 when a session is in this state, a call to open* will result in an open session,
 without UX or app-switching*/
FBSessionStateCreatedTokenLoaded        = 1,
/*! One of three pre-open session states indicating that an attempt to open the session
 is underway*/
FBSessionStateCreatedOpening            = 2,

/*! Open session state indicating user has logged in or a cached token is available */
FBSessionStateOpen                      = 1 | FB_SESSIONSTATEOPENBIT,
/*! Open session state indicating token has been extended, or the user has granted additional permissions */
FBSessionStateOpenTokenExtended         = 2 | FB_SESSIONSTATEOPENBIT,

/*! Closed session state indicating that a login attempt failed */
FBSessionStateClosedLoginFailed         = 1 | FB_SESSIONSTATETERMINALBIT, // NSError obj w/more info
/*! Closed session state indicating that the session was closed, but the users token
 remains cached on the device for later use */
FBSessionStateClosed                    = 2 | FB_SESSIONSTATETERMINALBIT, // "
};

这是一个错误还是出于某种原因，facebook 的代码应该真正打开一个新会话？我应该与状态的int 值而不是常量进行比较吗？为什么记录的值会与常数不一致？

...此外，记录状态在状态重新打开后，它记录为 513 或 514，这与任何常量不符。

Answer 1

根据常量的typedef枚举，1的状态为FBSessionStateCreatedTokenLoaded。评论说“两种初始会话状态之一，表明已加载缓存令牌；当会话处于此状态时，对 open* 的调用将导致打开会话，而无需 UX 或应用程序切换”。

所以我接受了这个建议，解决方案运行良好，会话在没有 UX 或应用切换的情况下打开：

    if (FBSession.activeSession.state == FBSessionStateCreatedTokenLoaded) {
        NSLog(@"fb session state created token loaded.");
        [FBSession.activeSession openWithCompletionHandler:^(FBSession *session, FBSessionState status, NSError *error) {
            if (FBSession.activeSession.state == FBSessionStateOpen) {
                // do stuff
            }
        }];
    }
    else if (FBSession.activeSession.state == FBSessionStateOpen
        || FBSession.activeSession.state == FBSessionStateOpenTokenExtended) {
        NSLog(@"fb session already open");
        // do stuff

    } else {
        NSLog(@"open new facebook session");
        // open new session...
    }