UISearchController 问题汇总

UISearchController配合UITableview，点击cell再次返回后，UISearchController无法获取焦点

解决办法：

    override func viewDidAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        self.definesPresentationContext = true
    }
    
    override func viewDidDisappear(_ animated: Bool) {
        super.viewDidAppear(animated)
        self.definesPresentationContext = false
    }