ios - 如何使用扩展设置 viewController 搜索栏的委托(delegate)？

Question

我创建了导航自定义类，我想装饰它，我采用了 NavDecoration.swift 类并声明了如下代码所示的扩展，我也在这个函数中添加了搜索条码，我想在中设置搜索条委托(delegate)此扩展但其给出的错误无法将类型“UIViewController”分配给类型“UISearchBarDelegate”

 extension UINavigationController {
 func makeBlackNavigationbar (viewController: UIViewController, animated: Bool) {

 viewController.navigationController?.navigationBar.backgroundColor? = UIColor.blackColor()
    let add = UIBarButtonItem(barButtonSystemItem: .Add, target: viewController, action: "addTapped")
    let play = UIBarButtonItem(title: "Play", style: .Plain, target: viewController, action: "addTapped")
   viewController.navigationItem.rightBarButtonItems = [add, play]

    let left = UIBarButtonItem(barButtonSystemItem: .Add, target: viewController, action: "addTapped")
    viewController.navigationItem.leftBarButtonItems = [left]

       let searchBar = UISearchBar(frame: CGRectZero)
        searchBar.placeholder = "Search"
        searchBar.delegate = viewController
        viewController.navigationItem.titleView = searchBar
}}

Answer 1

你必须遵守 UISearchBarDelegate 协议(protocol):

extension UINavigationController : UISearchBarDelegate {
   ...
}