WatchKit — 是什么，Apple Watch 和 watchOS 框架

class MainInterfaceController: WKInterfaceController {
    @IBOutlet weak var titleLabel: WKInterfaceLabel!
    @IBOutlet weak var actionButton: WKInterfaceButton!
    
    override func awake(with context: Any?) {
        super.awake(with: context)
        titleLabel.setText("你好，Watch！")
    }
    
    override func willActivate() {
        super.willActivate()
        actionButton.setTitle("开始")
    }
    
    @IBAction func didTapButton() {
        pushController(withName: "DetailController", context: nil)
    }
}

class SessionManager: NSObject, WCSessionDelegate {
    private let session = WCSession.default
    
    func activate() {
        session.delegate = self
        session.activate()
    }
    
    func sendDataToPhone(key: String, value: Any) {
        guard session.isReachable else { return }
        session.sendMessage([key: value],
            replyHandler: { response in
                print("Response: \(response)")
            },
            errorHandler: { error in
                print("Error: \(error.localizedDescription)")
            }
        )
    }
    
    func session(_ session: WCSession,
               didReceiveMessage message: [String: Any],
               replyHandler: @escaping ([String: Any]) -> Void) {
        handleIncomingData(message)
        replyHandler(["status": "ok"])
    }
}

class ComplicationController: NSObject, CLKComplicationDataSource {
    func getCurrentTimelineEntry(
        for complication: CLKComplication,
        withHandler handler: @escaping (CLKComplicationTimelineEntry?) -> Void
    ) {
        let template = CLKComplicationTemplateModularSmallSimpleText()
        template.textProvider = CLKSimpleTextProvider(text: "96%")
        let entry = CLKComplicationTimelineEntry(
            date: Date(),
            complicationTemplate: template
        )
        handler(entry)
    }
}

class ItemRowController: NSObject {
    @IBOutlet weak var itemLabel: WKInterfaceLabel!
    
    func configure(with text: String) {
        itemLabel.setText(text)
    }
}

class ListController: WKInterfaceController {
    @IBOutlet weak var itemsTable: WKInterfaceTable!
    private var items: [String] = []
    
    override func awake(with context: Any?) {
        super.awake(with: context)
        items = context as? [String] ?? []
        
        itemsTable.setNumberOfRows(items.count,
            withRowType: "ItemRow")
        for i in 0..if let row = itemsTable
                .rowController(at: i) as? ItemRowController {
                row.configure(with: items[i])
            }
        }
    }
}

class WorkoutManager: NSObject {
    private let healthStore = HKHealthStore()
    private var session: HKWorkoutSession!
    
    func startWorkout(activityType: HKWorkoutActivityType) {
        let config = HKWorkoutConfiguration()
        config.activityType = activityType
        config.locationType = .outdoor
        
        session = try! HKWorkoutSession(
            healthStore: healthStore,
            configuration: config
        )
        session.startActivity(with: Date())
    }
    
    func stopWorkout() {
        session.stopActivity(with: Date())
        session.end()
    }
}