uisearchbar 位置偏移的问题

QQ20180701-185545@2x.png

在一个modal出来的vc上，再次modal一个vc2，vc2里有这个searbar不知道为啥就有这个bug（viewdidload方法里加入到vc2的view里）

后来改成如下代码算是一个比较笨的解决方案

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];

    [self.headView addSubview:self.searchBar];
    self.searchBar.frame = CGRectMake(0, 20, kDeviceWidth, self.headViewHeight - 20);
    self.searchBar.text = _keyWord;

    [self.searchBar becomeFirstResponder];
}

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];

    [self.searchBar resignFirstResponder];
    [self.searchBar removeFromSuperview];
}