Question

我尝试如下创建自定义UINavigationController类-

class NavigationController: UINavigationController {
    private let user: User

    init(user: User, rootViewController: UIViewController) {
        self.user = user
        super.init(rootViewController: rootViewController)
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

以上代码在运行时失败，并出现以下错误-

致命错误：对类“ app.NavigationController”使用未实现的初始化程序“ init（nibName：bundle :)”

我试图通过添加初始化程序来解决此问题

class NavigationController: UINavigationController {
    private let user: User

    init(user: User, rootViewController: UIViewController) {
        self.user = user
        super.init(rootViewController: rootViewController)
    }

    override init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: Bundle?) {
        super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

编译器将引发错误“未在super.init调用中初始化属性'self.user'”。

有没有一种方法可以解决此问题，而无需将user属性设置为隐式展开的可选内容？

Answer 1

您可以执行以下操作：

class NavigationController: UINavigationController {
    private let user: User

    init(user: User, rootViewController: UIViewController, nibName nibNameOrNil: String? = nil, bundle nibBundleOrNil: Bundle? = nil) {
        self.user = user
        super.init(nibName: nil, bundle: nil)
        self.viewControllers = [rootViewController]
    }
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}
let vc = UIViewController()
let nc = NavigationController(user: User(), rootViewController: vc)

Answer 2

不要像这样初始化用户。在 Controller 中，您将其称为NavigationController：

将private let user : User更改为

var user : User!
初始化您的NavigationController
然后将用户设置为：

navigationController.user = self.user

self.user是您要赋予navigationController

的变量

Answer 3

方法

google.appengine.api.users.create_login_url

是指定的初始化程序，这意味着它将始终被调用，而

override init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: Bundle?)

是一个便利初始化程序，出于便利原因可能会被调用。当指定的初始化程序被调用时，您的类具有未初始化的用户常数。您可以将user切换为可选的var，并使用nil对其进行初始化。

Answer 4

使用带有自定义参数的便捷初始化并调用指定的初始化程序来设置root viewController

final class NavigationController: UINavigationController {
    
    private var user: User?
    
    convenience init(rootViewController: UIViewController, user: User) {
        self.init(rootViewController: rootViewController)
        self.user = user
    }
    
    override init(rootViewController: UIViewController) {
        super.init(rootViewController: rootViewController)
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

/// How to use

let user = User()
let rootViewController = UIViewController()
let navigationController = NavigationController(rootViewController: rootViewController, user: user)

如何使用自定义init创建自定义UINavigationController类？

4 个答案: