WatchConnectivity接收苹果手表心率消息类型转换失败及报错求助

• 开发过程中触发((Any) throws -> Bool) throws -> Optional<Any> cannot conform to 'BinaryInteger'类型不匹配报错
• 项目为苹果手表采集心率同步至iPhone的示例项目，当前卡在WatchConnectivity会话传输的[String: Any]类型消息转换环节，已研究WatchConnectivity相关开发逻辑3天
• 已验证手表端消息可正常传输到iOS端，仅差消息接入心率更新逻辑，初步判定guard let语句导致didReceiveMessage函数提前终止
• 确认只要将["rate": 61]格式的消息解包为Double类型的数值61，即可通过guard let校验保证函数正常执行

• 存在附加报错NO with WCErrorCodeDeliveryFailed，已按照现有公开方案调整逻辑仍会复现，经判断该报错与上述类型转换问题无关联
  

import Foundation
import WatchConnectivity

protocol WatchKitConnectionDelegate: AnyObject {
    func didFinishedActiveSession()
    func updateLatestHeartRate(_ LatestHeartRate: Double)
}

protocol WatchKitConnectionProtocol {
    func startSession()
    func sendMessage(message: [String : AnyObject], replyHandler: (([String : AnyObject]) -> Void)?, errorHandler: ((NSError) -> Void)?)
}

class WatchKitConnection: NSObject {
    static let shared = WatchKitConnection()
    weak var delegate: WatchKitConnectionDelegate?
    
    private override init() {
        super.init()
    }
    
    func sendHeartRate(rate: Int) {
        WCSession.default.sendMessage(["rate": rate], replyHandler: nil) { error in
            print("Failed to send message: \(error)")
        }

        print("from iOS watchkit connection")
    }
}

extension WatchKitConnection: WatchKitConnectionProtocol {
    func startSession() {
        session?.delegate = self
        session?.activate()
    }
    
    func sendMessage(message: [String : AnyObject],
                     replyHandler: (([String : AnyObject]) -> Void)? = nil,
                     errorHandler: ((NSError) -> Void)? = nil)
    
    {
        validReachableSession?.sendMessage(message, replyHandler: { (result) in
            print(result)
            print("success in phone sendmessage function")
        }, errorHandler: { (error) in
            print("error in phone sendmessage function")
            print(error)
        })
    }
    
}

extension WatchKitConnection: WCSessionDelegate {
    func session(_ session: WCSession, didReceiveMessage message: [String : Any]) {
        print("didReceiveMessage from watch")
        print(message)
        
        delegate?.updateLatestHeartRate(Double(message.values.first))
        
        guard let heartRate = message.values.first as? String? else {
            return
        }
        guard let heartRateDouble = Double(heartRate!) else {
            return
        }
        
        print("printing heartRate double from message\(heartRateDouble)")
        
        delegate?.updateLatestHeartRate(heartRateDouble)
        
        print("updateLatestHeartRate")
    }
}

核心问题原因 #

手表端发送的心率值为Int类型，原有代码错误尝试将Int值转为String类型，导致guard let校验失败提前返回，同时message.values.first为Any类型，无法直接传入Double构造器触发类型不匹配报错。

修正代码 #

1. 先在WatchKitConnection类内补充缺失的WCSession相关属性

class WatchKitConnection: NSObject {
    static let shared = WatchKitConnection()
    weak var delegate: WatchKitConnectionDelegate?
    // 补充session定义
    private let session: WCSession? = WCSession.isSupported() ? WCSession.default : nil
    // 补充可用会话判断属性
    private var validReachableSession: WCSession? {
        guard let session = session, session.isReachable else { return nil }
        return session
    }
    
    // 原有其他代码不变
    private override init() {
        super.init()
    }
    // ...
}

2. 替换原有didReceiveMessage方法逻辑

func session(_ session: WCSession, didReceiveMessage message: [String : Any]) {
    print("didReceiveMessage from watch")
    print(message)
    // 直接按key取值，避免遍历values取到错误值
    guard let heartRate = message["rate"] as? Int else {
        return
    }
    // Int转Double无需二次解析
    let heartRateDouble = Double(heartRate)
    print("printing heartRate double from message\(heartRateDouble)")
    delegate?.updateLatestHeartRate(heartRateDouble)
    print("updateLatestHeartRate")
}

修改后即可解决类型不匹配报错，guard let校验不会提前终止函数运行。

内容的提问来源于stack exchange，提问作者Michael