uisearchDisplayController放在tableview里下拉刷新状态出现遮挡

代码如下

- (void)viewDidLoad {
    [super viewDidLoad];

    UISearchBar * searchBar =[[UISearchBar alloc]initWithFrame:CGRectMake(0, 0, 320, 44)];
    self.tableView.tableHeaderView=searchBar;

    self.searchController =[[UISearchDisplayController alloc]initWithSearchBar:searchBar contentsController:self];

    //
    //(refreshing)
    //
    [self.tableView setContentInset:UIEdgeInsetsMake(128, 0, 0, 0)];
}

问题如图：

问题：searchBar的视图中clipsToBounds
为yes

解决方法：自定义searchbar，重写layoutSubviews方法，把searchbar的所有subview的clipsToBounds重置为no

-(void)layoutSubviews{
    [super layoutSubviews];
    for (UIView * view in self.subviews) {
        view.clipsToBounds=NO;
    }
}