Watch Connectivity首次使用，但此后没有

Question

I've tested on the Simulator and Device, somehow Watch Connectivity stops working after it's used once.

I'm passing data from Watch -> iPhone, and it only works once and then stops after that.

Any ideas?

iPhone ViewController :

var session: WCSession?

override func viewDidLoad() {
    super.viewDidLoad()
    if WCSession.isSupported() {
        session = WCSession.default()
        session?.delegate = self
        session?.activate()
    }
}

func session(_ session: WCSession, didReceiveApplicationContext applicationContext: [String : Any]) {
    // Received Application Context from Watch
    let type = applicationContext["watchType"]
    print("Type iPhone: \(type)")

    DispatchQueue.main.async {
        self.type.text = "Type: \(type)"
    }

}

Watch InterfaceController :

let session = WCSession.default()

override func awake(withContext context: Any?) {
    super.awake(withContext: context)

    if WCSession.isSupported() {
        session.delegate = self
        session.activate()
    }
}

@IBAction func startPressed() {
    saveEverything()
}

func saveEverything() {
    let watchContextType = ["watchType" : "Boxing/Running"]

    do {
        print("Type Watch: \(watchContextType)")
        try session.updateApplicationContext(watchContextType)
    } catch {
        print("Didn't work")
    }
}

Answer 1

When you use the updateApplicationContext() , you need to change the parameters for each call, otherwise the msg will not be delivered. I belive this is to conserve battery.

Anyway, try sending your message using sendMessage() or sendMessageData() , then the messages get delivered each time, even when they have the same contents. And, they are higher priority than updateApplicationContext so it's win-win :)

Here is the documentation: https://developer.apple.com/library/content/documentation/General/Conceptual/WatchKitProgrammingGuide/SharingData.html#//apple_ref/doc/uid/TP40014969-CH29-SW1

Answer 2

If you want to Drain Battery of your apple watch app Quickly then above technique of @Jens is well and good.

---

Instead of shifting from updateApplicationContext() to sendMessage() better make small change in your project to get Desired result.

---

I will explain the question scenario and then solution along with Demo app :-

 @IBAction func sliderChange(_ value: Float)

{
    let str:String?
    switch value {
    case 0...7 :
          str = "Running"
    case 8...14 :
          str = "Sleeping"
    default:
        str = "normal"
    }
     updateContext(value: str!)
}

func updateContext(value:String) {
    let dictionary = [ "watchType" : value ]
    do {
        print("update application context is called do statemet")
        try session?.updateApplicationContext(dictionary)
    }
    catch{
        print("this is the catch statement")
    }
}

With update in slider Values in Watch ,iPhone values get updated .As you can see there is repetition of values for iPhone ie

When sliderValue are from 0 to 7 values remain "Running" && "Sleeping" for 8 to 14 .

App work fine if I varies values of slide and desired result is reflected in iPhone in normal scenario.

Scenrio where it fails :- i)Change the slider values from 0 to 3 then "Running" is reflected in iPhone. Thant's fine . ii)Now close the iPhone application then change the slider values from 3 to 5 no we can see real problem when iPhone is opened back. iii) Values is not triggered to iPhone .

Due to internal caching mechanism of updateApplicationContext() restrict to trigger of duplicate values to iPhone .

Store the last updated state in didReceiveApplicationContext() and display state according to stored value .

override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        checkStatus()
        updateSavedState()
    }
    func checkStatus() {
        print("check status")
        if WCSession.isSupported() {
            session = WCSession.default()
            session?.delegate = self
            session?.activate()
        }
    }

     func session(_ session: WCSession, didReceiveApplicationContext    applicationContext: [String : Any]) {
        let type = applicationContext["watchType"]!
         DispatchQueue.main.async {
            self.updateLabel.text =  " Type: \(type)"
            UserDefaults.standard.set(type, forKey: "savedState") //setObject
        }
    }

    func updateSavedState() {
        self.updateLabel.text = UserDefaults.standard.string(forKey: "savedState")
    }

Now everything is work perfect. Demo App .