发现一个好奇怪的问题，我直接
tableView.tableHeaderView = searchController.searchBar
这样是正常的。可以进行搜索
但是把searchController.searchBar放到一个UIView里面，点击就没有反应了，搜索框似乎无法获得焦点，真奇怪，代码如下所示：
var searchhead:UILabel = UILabel(frame: CGRectMake(0,0, self.view.frame.size.width, 100.0))
var searchhead_1:UILabel = UILabel(frame: CGRectMake(0,0, self.view.frame.size.width, 45.0))
searchhead_1.text = "搜索"
searchhead.addSubview(searchhead_1)
var searchhead_2:UIView = UIView(frame: CGRectMake(0,45, self.view.frame.size.width, 55.0))
searchhead_2.addSubview(searchController.searchBar)
searchhead.addSubview(searchhead_2)
tableView.tableHeaderView = searchhead
