Unbalanced calls to begin/end appearance transitions for

2012-08-17 10:18:02.398[401:707] Unbalanced calls to begin/end appearance transitions for .

2012-08-17 10:18:02.641[401:707] Finishing up a navigation transition in an unexpected state. Navigation Bar subview tree might get corrupted.

由于上个uivewcontroller的动画没做完，导致下一个的页面无法顺利压栈，这个只需要上一个页面返回的时候不要做动画就可以了。

        [NSTimer scheduledTimerWithTimeInterval:0.5
                                         target:self
                                       selector:@selector(backLogin)
                                       userInfo:nil
                                        repeats:NO];