ios7上UISearchBar和UITableView下拉刷新的时候阴影解决

_searchBar = [[UISearchBar
alloc]initWithFrame:CGRectMake(0,
0, 320,
44)];

_searchBar.delegate =
self;

//不贴view下拉就会有阴影

UIView *view = [[UIView
alloc] initWithFrame:CGRectMake(0,
0, 320,
44)];

[view addSubview:_searchBar];

self.tableView.tableHeaderView = view;

不能直接：

self.tableView.tableHeaderView = view;