ios safeAreaInsets输出不正确问题

UITableView *ta = [[UITableView alloc]initWithFrame:CGRectMake(0, 0, jqW, jqH) style:UITableViewStylePlain];
    [self.view addSubview:ta];
    ta.delegate = self;
    ta.dataSource = self;
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        NSLog(@"%@",NSStringFromUIEdgeInsets(self.view.safeAreaInsets));
//{64, 0, 0, 0}
        NSLog(@"%@",NSStringFromUIEdgeInsets(ta.safeAreaInsets));
//{64, 0, 0, 0}
    });

需要加上一个延时，待视图显示出来了，打印的结果才正确.

SafeAreaInsets值反映了view被覆盖的部分
additionalSafeAreaInsets：在原有基础上加减响应的安全距离