Facebook iOS SDK 3.1 在随后调用 FBSession openWithBehavior 时崩溃

Question

如果我们在调用 closeAndClearTokenInformation 之后调用 openWithBehavior，则会导致 EXC_BAD_ACCESS。无论是使用原生 iOS 内置对话框还是快速切换对话框之一。

我们第一次登录FB的代码：

if (![FBSession activeSession]) {
    #ifdef FREE_APP
        NSString* suffix = @"free";
    #else
        NSString* suffix = @"paid";
    #endif
    FBSession *session = [[[FBSession alloc] initWithAppID:@"111111111111111"
                            permissions:permissions
                        urlSchemeSuffix:suffix
                     tokenCacheStrategy:nil] autorelease];
    [FBSession setActiveSession:session];
} 
else if ([FBSession activeSession].isOpen)
    [[FBSession activeSession] close];

[[FBSession activeSession] openWithBehavior:FBSessionLoginBehaviorUseSystemAccountIfPresent
              completionHandler:^(FBSession *session, FBSessionState state, NSError *error) {
                                     [self sessionStateChanged:session state:state error:error];
                                 }];

我们的代码要注销，之后上面的代码在openWithBehavior之后失败：

[[FBSession activeSession] closeAndClearTokenInformation];

我最初使用的是 openActiveSessionWithReadPermissions 而不是 openWithBehavior，如 3.1 文档中所述，它不会崩溃，但从 FB 应用程序/Safari 切换回的应用程序不起作用。也许是因为需要后缀？如果修复应用程序切换并返回最简单，请告知。

谢谢。

Answer 1

当我在 5.x 模拟器中运行时，我看到了来自 openWithBehavior 的一个额外的、非常有用的错误消息，然后在源代码中查找它使事情变得更加清晰：

if (!(self.state == FBSessionStateCreated ||
      self.state == FBSessionStateCreatedTokenLoaded)) {
    // login may only be called once, and only from one of the two initial states
    [[NSException exceptionWithName:FBInvalidOperationException
                             reason:@"FBSession: an attempt was made to open an already opened or closed session"
                           userInfo:nil]
     raise];
}

我已将代码更改为在调用 openWithBehavior 之前始终创建一个新会话，这似乎很开心。

更新： 这是检查活动会话的更新代码，然后将其关闭，然后始终实例化新会话...

  - (BOOL)openSessionWithAllowLoginUI:(BOOL)allowLoginUI {


      if ([FBSession activeSession])
         [[FBSession activeSession] closeAndClearTokenInformation];

      #ifdef FREE_APP
         NSString* suffix = @"free";
      #else
         NSString* suffix = @"paid";
      #endif

      NSArray *permissions = [[NSArray alloc] initWithObjects:@"email", nil];

      FBSession *session = [[FBSession alloc] initWithAppID:mFacebookID
                                               permissions:permissions
                                           urlSchemeSuffix:suffix
                                        tokenCacheStrategy:nil]; 

      [FBSession setActiveSession:session];

      If (allowLoginUI == YES) {
        NSLog(@"Calling openWithBehavior");
        [[FBSession activeSession] openWithBehavior:FBSessionLoginBehaviorUseSystemAccountIfPresent
                                   completionHandler:^(FBSession *session, FBSessionState state, NSError *error)
                                   {
                                      [self sessionStateChanged:session state:state error:error];
                                   }
        ];
     } else if(session.state == FBSessionStateCreatedTokenLoaded) {
        NSLog(@"Calling openWith completion handler");
        [session openWithCompletionHandler:^(FBSession *_session, FBSessionState status, NSError *error)
                                            {   [self sessionStateChanged:session state:status error:error];}
        ];
     }

     [session release];   

     return true;
  }