Unbalanced calls to begin/end appearance transitions for 解决方法

自定义TabBarController Push下一级Controller时 会报这样的错误：Unbalanced calls to begin/end appearance transitions for <UIVIewController>

自定义了TabBarController 之后必须实现以下方法：具体代码在代码块中。

-(void)viewWillAppear:(BOOL)animated
{
    [self.selectedViewController beginAppearanceTransition: YES animated: animated];
}

-(void) viewDidAppear:(BOOL)animated
{
    [self.selectedViewController endAppearanceTransition];
}

-(void) viewWillDisappear:(BOOL)animated
{
    [self.selectedViewController beginAppearanceTransition: NO animated: animated];
}

-(void) viewDidDisappear:(BOOL)animated
{
    [self.selectedViewController endAppearanceTransition];
}

参考blog：http://blog.csdn.net/u013020103/article/details/28866295