ReachabilitySwift通知集成报错：无法识别reachabilityChanged方法

这个问题我之前也碰到过，核心原因是Swift方法默认不暴露给Objective-C运行时，而NotificationCenter的addObserver依赖Objective-C的Selector机制，再加上你的Selector签名和方法定义不匹配，才导致了"未解析的标识符"错误。下面是具体的修复步骤：

1. 给监听方法添加@objc修饰符 #

Swift中，只有标记了@objc的方法才能被Objective-C运行时识别，所以你需要给reachabilityChanged方法加上这个修饰符：

@objc func reachabilityChanged(note: Notification) {
    let reachability = note.object as! Reachability
    switch reachability.connection {
    case .wifi:
        print("Reachable via WiFi")
    case .cellular:
        print("Reachable via Cellular")
    case .none:
        print("Network not reachable")
    }
}

2. 修正Selector的签名匹配 #

你的Selector写的是#selector(reachabilityChanged(_:))，但方法定义是reachabilityChanged(note:)，签名不匹配。有两种修正方式：

• 方式一：保持方法参数名，Selector写成带参数名的形式：

NotificationCenter.default.addObserver(self, 
                                       selector: #selector(reachabilityChanged(note:)), 
                                       name: .reachabilityChanged, 
                                       object: centralreachability)

• 方式二：修改方法参数为下划线，匹配原Selector写法：

@objc func reachabilityChanged(_ note: Notification) {
    // 方法内容不变
}
// 此时Selector用#selector(reachabilityChanged(_:))就没问题了

3. 修复Reachability实例的可选性问题 #

你定义的let centralreachability = Reachability()，如果Reachability的初始化方法是可失败的（比如init?()），这里应该改成可选类型，避免后续可选链的不必要使用：

var centralreachability: Reachability? = Reachability()

完整修正后的代码片段 #

class AppDelegate: UIResponder, UIApplicationDelegate {
    var window: UIWindow?
    struct Constants {
        public static let googleApi = "xxx"
    }
    var centralreachability: Reachability? = Reachability()
    
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        // 修正Selector签名
        NotificationCenter.default.addObserver(self, 
                                               selector: #selector(reachabilityChanged(note:)), 
                                               name: .reachabilityChanged, 
                                               object: centralreachability)
        do{
            try centralreachability?.startNotifier()
        } catch{
            print("could not start reachability notifier")
        }
        NetworkActivityIndicatorManager.shared.isEnabled = true
        return true
    }
    
    // 添加@objc修饰符
    @objc func reachabilityChanged(note: Notification) {
        guard let reachability = note.object as? Reachability else { return }
        switch reachability.connection {
        case .wifi:
            print("Reachable via WiFi")
        case .cellular:
            print("Reachable via Cellular")
        case .none:
            print("Network not reachable")
        }
    }
    // ... rest of AppDelegate
}

另外，建议在deinit方法中移除通知观察者，避免内存泄漏：

deinit {
    NotificationCenter.default.removeObserver(self)
    centralreachability?.stopNotifier()
}

内容的提问来源于stack exchange，提问作者MW_DEVEL