如何复用导航栏按钮？iOS导航控制器多页面开发疑问

嘿，针对你这个导航栏刷新按钮（连同余额标签）的复用需求，我给你整理了几个iOS开发里常用且实用的方案，你可以根据项目的结构和需求来选择：

这是最直观、代码复用性最高的方式——把导航栏元素的创建、刷新逻辑都封装到一个基类里，需要用到这些功能的ViewController直接继承这个基类就行。

代码示例： #

首先创建基类：

class BaseBalanceViewController: UIViewController {
    // 复用的余额标签
    var balanceLabel: UILabel!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        setupNavigationBarComponents()
    }
    
    // 统一创建导航栏元素
    private func setupNavigationBarComponents() {
        // 初始化余额标签
        balanceLabel = UILabel()
        balanceLabel.font = UIFont.systemFont(ofSize: 16, weight: .semibold)
        balanceLabel.textColor = .label
        navigationItem.leftBarButtonItem = UIBarButtonItem(customView: balanceLabel)
        
        // 初始化刷新按钮
        let refreshButton = UIBarButtonItem(barButtonSystemItem: .refresh, target: self, action: #selector(refreshBalanceAction))
        navigationItem.rightBarButtonItem = refreshButton
    }
    
    // 通用的刷新逻辑，子类可以重写自定义行为
    @objc func refreshBalanceAction() {
        let operation = GetInfoOperation(/* 这里可以传入通用参数，子类重写时替换为自己的参数 */)
        operation.completionBlock = { [weak self] in
            DispatchQueue.main.async {
                guard let balance = operation.output?.value?.balance else { return }
                self?.balanceLabel.text = "余额：\(balance)"
            }
        }
        OperationQueue().addOperation(operation)
    }
}

然后你的第一个ViewController就可以这样用：

class FirstViewController: BaseBalanceViewController {
    // 如果需要自定义刷新逻辑，直接重写基类方法即可
    override func refreshBalanceAction() {
        // 这里写当前VC特有的请求逻辑，或者调用super保持通用逻辑
        let operation = GetInfoOperation(/* 传入当前VC需要的参数 */)
        operation.completionBlock = { [weak self] in
            DispatchQueue.main.async {
                guard let balance = operation.output?.value?.balance else { return }
                self?.balanceLabel.text = "当前账户余额：\(balance)"
            }
        }
        OperationQueue().addOperation(operation)
    }
}

适用场景： #

多个ViewController的导航栏逻辑相似，且没有复杂的继承链冲突时，优先选这个方案，逻辑集中，维护起来也方便。

如果你的ViewController已经继承了其他类（没法再继承基类），可以用扩展来封装导航栏元素的创建和点击逻辑，灵活性更高。

代码示例： #

extension UIViewController {
    // 调用这个方法来设置导航栏元素，返回余额标签方便后续更新
    func setupBalanceNavigationElements(withRefreshHandler handler: @escaping () -> Void) -> UILabel {
        // 创建余额标签
        let balanceLabel = UILabel()
        balanceLabel.font = UIFont.systemFont(ofSize: 16, weight: .semibold)
        balanceLabel.textColor = .label
        navigationItem.leftBarButtonItem = UIBarButtonItem(customView: balanceLabel)
        
        // 创建刷新按钮
        let refreshButton = UIBarButtonItem(barButtonSystemItem: .refresh, target: self, action: #selector(refreshTriggered))
        navigationItem.rightBarButtonItem = refreshButton
        
        // 用关联对象保存刷新回调
        objc_setAssociatedObject(self, &RefreshHandlerKey, handler, .OBJC_ASSOCIATION_COPY_NONATOMIC)
        
        return balanceLabel
    }
    
    @objc private func refreshTriggered() {
        if let handler = objc_getAssociatedObject(self, &RefreshHandlerKey) as? () -> Void {
            handler()
        }
    }
}

// 用于关联对象的唯一Key
private var RefreshHandlerKey: UInt8 = 0

然后在你的ViewController里调用：

class FirstViewController: UIViewController {
    private var balanceLabel: UILabel!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // 设置导航栏元素，并传入刷新回调
        balanceLabel = setupBalanceNavigationElements { [weak self] in
            self?.performBalanceRefresh()
        }
    }
    
    private func performBalanceRefresh() {
        let operation = GetInfoOperation(...)
        operation.completionBlock = { [weak self] in
            DispatchQueue.main.async {
                guard let balance = operation.output?.value?.balance else { return }
                self?.balanceLabel.text = "余额：\(balance)"
            }
        }
        OperationQueue().addOperation(operation)
    }
}

适用场景： #

不想改变现有继承链，或者只需要给少数几个ViewController添加这个功能时，用扩展更灵活。

如果希望整个导航栈里的ViewController都能统一复用这个导航栏元素，或者需要全局控制显示逻辑，可以自定义UINavigationController，通过协议来规范ViewController的行为。

代码示例： #

首先定义协议，约定需要刷新功能的ViewController要实现的内容：

protocol BalanceRefreshable: UIViewController {
    var balanceLabel: UILabel? { get set }
    func refreshBalance()
}

// 协议的默认实现（可选，提供通用逻辑）
extension BalanceRefreshable {
    func refreshBalance() {
        let operation = GetInfoOperation(...)
        operation.completionBlock = { [weak self] in
            DispatchQueue.main.async {
                guard let balance = operation.output?.value?.balance else { return }
                self?.balanceLabel?.text = "余额：\(balance)"
            }
        }
        OperationQueue().addOperation(operation)
    }
}

然后自定义导航控制器：

class BalanceNavigationController: UINavigationController {
    override func pushViewController(_ viewController: UIViewController, animated: Bool) {
        super.pushViewController(viewController, animated: animated)
        // 给实现了协议的ViewController添加导航栏元素
        if let balanceVC = viewController as? BalanceRefreshable {
            setupBalanceNavigationElements(for: balanceVC)
        }
    }
    
    private func setupBalanceNavigationElements(for vc: BalanceRefreshable) {
        let balanceLabel = UILabel()
        balanceLabel.font = UIFont.systemFont(ofSize: 16, weight: .semibold)
        balanceLabel.textColor = .label
        vc.navigationItem.leftBarButtonItem = UIBarButtonItem(customView: balanceLabel)
        
        let refreshButton = UIBarButtonItem(barButtonSystemItem: .refresh, target: vc, action: #selector(vc.refreshBalance))
        vc.navigationItem.rightBarButtonItem = refreshButton
        
        // 把标签传给ViewController，方便后续更新
        vc.balanceLabel = balanceLabel
    }
}

最后让你的ViewController实现协议：

class FirstViewController: UIViewController, BalanceRefreshable {
    var balanceLabel: UILabel?
    
    // 可以重写refreshBalance方法自定义逻辑
    func refreshBalance() {
        let operation = GetInfoOperation(/* 自定义参数 */)
        operation.completionBlock = { [weak self] in
            DispatchQueue.main.async {
                guard let balance = operation.output?.value?.balance else { return }
                self?.balanceLabel?.text = "我的账户余额：\(balance)"
            }
        }
        OperationQueue().addOperation(operation)
    }
}

适用场景： #

整个导航栈的ViewController都需要这类导航栏元素，或者需要统一控制导航栏的显示逻辑时，这个方案更合适。

内容的提问来源于stack exchange，提问作者FuzzzzyBoy