从一个table view 的单元格导航到细节页，报下面的错误：

nested push animation can result in corrupted navigation bar

Finishing up a navigation transition in an unexpected state. Navigation Bar subview tree might get corrupted.

原因是下面的函数多写了一句performSegueWithIdentifier，注释掉即可。

– (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath

{

  [self performSegueWithIdentifier:@”QuestionDetail”sender:self];

}