面试题：Swift在HomeKit智能家居控制中如何处理设备连接状态

原理：在Swift的HomeKit框架中，通过HMHomeManager和HMHome对象来管理家庭和设备。可以为HMHome对象的accessories数组中的每个HMAccessory添加连接状态变化的监听。HMAccessory的连接状态是通过HMAccessoryConnectionState枚举来表示的，当状态变化时，会触发相应的回调。
关键代码片段：

import HomeKit

class HomeKitManager {
    let homeManager = HMHomeManager()

    init() {
        homeManager.delegate = self
        homeManager.requestAccess { (success, error) in
            if success {
                // 成功获取访问权限
                self.fetchHomes()
            } else {
                print("Failed to get access: \(error?.localizedDescription ?? "Unknown error")")
            }
        }
    }

    func fetchHomes() {
        homeManager.homes { (homes, error) in
            if let homes = homes {
                for home in homes {
                    self.addAccessoryObservers(for: home)
                }
            } else {
                print("Failed to fetch homes: \(error?.localizedDescription ?? "Unknown error")")
            }
        }
    }

    func addAccessoryObservers(for home: HMHome) {
        for accessory in home.accessories {
            accessory.observe(\.connectionState, options: [.new, .old]) { (accessory, change) in
                guard let newState = change.newValue, let oldState = change.oldValue else { return }
                if newState != oldState {
                    self.handleAccessoryConnectionChange(accessory, oldState: oldState, newState: newState)
                }
            }
        }
    }

    func handleAccessoryConnectionChange(_ accessory: HMAccessory, oldState: HMAccessory.ConnectionState, newState: HMAccessory.ConnectionState) {
        switch newState {
        case .connected:
            print("\(accessory.name) connected.")
        case .connecting:
            print("\(accessory.name) is connecting.")
        case .disconnected:
            print("\(accessory.name) disconnected.")
        @unknown default:
            print("\(accessory.name) connection state changed to an unknown state.")
        }
    }
}

extension HomeKitManager: HMHomeManagerDelegate {
    func homeManagerDidUpdateHomes(_ manager: HMHomeManager) {
        fetchHomes()
    }
}

在上述代码中：

HomeKitManager类负责管理HomeKit相关操作。
init方法中请求HomeKit访问权限，并在获取权限后调用fetchHomes。
fetchHomes方法获取所有家庭，并为每个家庭中的设备添加连接状态变化的观察者。
addAccessoryObservers方法为每个HMAccessory添加connectionState属性变化的观察者。
handleAccessoryConnectionChange方法处理设备连接状态变化，根据不同的HMAccessory.ConnectionState进行相应处理。
HMHomeManagerDelegate的homeManagerDidUpdateHomes方法在家庭列表更新时重新获取家庭并添加观察者。

面试题：Swift在HomeKit智能家居控制中如何处理设备连接状态

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