iOS11

_tab.estimatedRowHeight = 0;

if (@available(iOS 11.0, *)) {

//当有heightForHeader delegate时设置

_tab.estimatedSectionHeaderHeight = 0;

//当有heightForFooter delegate时设置

_tab.estimatedSectionFooterHeight = 0;

}

/解决因为隐藏导航栏导致页面下沉的问题
if (@available(iOS 11.0, *)) {
_contentTV.contentInsetAdjustmentBehavior=UIScrollViewContentInsetAdjustmentNever;
} else {
}