How can I send a data back to iPhone using WatchConnectivity - ios

Question

I have a Habits app with several counters. Now I figure out how to send a counter's value to iWatch. The question is: when I push a button and change a counter's value on iWatch (for example +1) how can I send the data back to iPhone?
To send a count value from iPhone I have a code in ViewController:
func session(_ session: WCSession, activationDidCompleteWith activationState: WCSessionActivationState, error: Error?) { }
func sessionDidBecomeInactive(_ session: WCSession) { }
func sessionDidDeactivate(_ session: WCSession) { }
var session: WCSession?
var count = 0
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
if WCSession.isSupported() {
session = WCSession.default
session?.delegate = self
session?.activate()
}
}
#IBAction func addPlusOne(_ sender: UIButton) {
let count += 1
let sendHabit = String(count)
if let validSession = session {
let iPhoneAppCount = ["Habits": sendHabit]
do {
try validSession.updateApplicationContext(iPhoneAppCount)
} catch {
print("Something went wrong")
}
}
To receive the count value to iWatch I have code In InterfaceController:
let session = WCSession.default
override func awake(withContext context: Any?) {
super.awake(withContext: context)
processApplicationContext()
processApplicationCount()
session.delegate = self
session.activate()
}
func processApplicationCount() {
if let iPhoneContext = session.receivedApplicationContext as? [String : String] {
displayLabel.setText(iPhoneContext["Habits"])
}
}
func session(_ session: WCSession, didReceiveApplicationContext applicationContext: [String : Any]) {
DispatchQueue.main.async() {
self.processApplicationCount()
}
}

Answer 1

Transferring data from Apple Watch to iPhone is very similar to vice versa.
For global variables you can use updateApplicationContext() of WCSession from the Watch:
let session = WCSession.default()
if session.activationState == .activated {
session.updateApplicationContext(["my_global": g_myGlobal])
}
Then on the phone you should assign a delegate to the WCSession and implement the following:
func session(_ session: WCSession, didReceiveApplicationContext applicationContext: [String : Any]) {
let receivedGlobal = applicationContext["my_global"] as? TypeOfTheGlobal
}