将原点移动到navigationBar下面(或UIScrollView和 cell加载子视图偏移64问题)

    if ([[[UIDevice currentDevice] systemName] floatValue]> 7.0?YES:NO)  {
      self.edgesForExtendedLayout = UIRectEdgeNone; (iOS7.0以上兼容适配)
      self.automaticallyAdjustsScrollViewInsets=NO;(iOS7.0以下兼容适配)
    }