selector - 收到此错误。'UIViewController' 没有可见的@interface 声明选择器'presentViewController'

Question

问题出在 if([[topViewController presentViewController]行：

(void)sessionStateChanged:(FBSession *)session
      state:(FBSessionState) state
                      error:(NSError *)error
{
    switch (state) {
        case FBSessionStateOpen: {
            UIViewController *topViewController =
            self.navController topViewController];

            if ([[topViewController presentViewController]
                 isKindOfClass:[PBLoginViewController class]]) {
                [topViewController dismissViewControllerAnimated:YES completion:nil];