如何使用扩展设置 viewController 搜索栏的委托？答案

【问题标题】：How to set delegate of search bar of viewController using extension?如何使用扩展设置 viewController 搜索栏的委托？
【发布时间】：2016-05-25 13:02:14
【问题描述】：

我创建了导航自定义类，我想装饰它，我使用 NavDecoration.swift 类并声明了如下代码所示的扩展，我在这个函数中也添加了搜索栏代码，我想在其中设置搜索栏委托此扩展名，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
}}

【问题讨论】：

标签： ios objective-c iphone cocoa-touch swift2

【解决方案1】：

你必须符合 UISearchBarDelegate 协议：

extension UINavigationController : UISearchBarDelegate {
   ...
}

【讨论】：

我已经准备好了，当我做 searchBar.delegate = viewController 时，它给了我同样的错误，不能将类型“UIViewController”分配给类型“UISearchBarDelegate”
您指定 UiViewController 而不是 UINAvigationController 作为委托。如果您的扩展名如上，则必须设置 searchBar.delegate = viewController.navigationController 。

【解决方案2】：

**我只更改了几行代码**

  extension UIViewController : UISearchBarDelegate {

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
}}

【讨论】：