How to run watch app in the background using WKExtendedRuntimeSession - swift

Question

Thank you for taking a look at this page.
I am developing a Watch App and would like to do some background data processing in SwiftUI.
I tried to run it using WKExtendedRuntimeSession, but it doesn't seem to be running when it becomes inactive.
import SwiftUI
#main
struct FirebaseExample_Watch_AppApp: App {
var session = WKExtendedRuntimeSession()
init() {
session.start()
// MARK:- Extended Runtime Session Delegate Methods
func extendedRuntimeSessionDidStart(_ extendedRuntimeSession: WKExtendedRuntimeSession) {
print(1)
}
func extendedRuntimeSessionWillExpire(_ extendedRuntimeSession: WKExtendedRuntimeSession) {
print(2)
}
func extendedRuntimeSession(_ extendedRuntimeSession: WKExtendedRuntimeSession, didInvalidateWith reason: WKExtendedRuntimeSessionInvalidationReason, error: Error?) {
print(3)
}
}
var body: some Scene {
WindowGroup {
ContentView()
}
}
}
But the result is nothing happens the moment I put my arm down and the app screen disappears.
I alse tried to do this;
　　　　 　　　　　　　　　　　　
init() {
　　　　　　　　func startTimerButtonPressed() {
print(WKApplicationState.RawValue())
var session = WKExtendedRuntimeSession()
session.start()
print(WKExtendedRuntimeSessionState.RawValue())
}
The results are all zeros and do not appear to be initiated.
If you are familiar with WKExtendedRuntimeSession, please let me know how to run it.
Reference
https://developer.apple.com/documentation/watchkit/wkextendedruntimesession

Answer 1

You are not setting a delegate for your session. A possible implementation would look like this:
#main
struct TestWatchOSOnly_Watch_AppApp: App {
#State var session = WKExtendedRuntimeSession()
//define and create the delegate
#State var delegate = WKDelegate()
var body: some Scene {
WindowGroup {
ContentView()
.onAppear{
//create a new session
session = WKExtendedRuntimeSession()
//assign the delegate
session.delegate = delegate
//start the session
session.start()
}
}
}
}
// define the delegate and its methods
class WKDelegate: NSObject, WKExtendedRuntimeSessionDelegate{
func extendedRuntimeSession(_ extendedRuntimeSession: WKExtendedRuntimeSession, didInvalidateWith reason: WKExtendedRuntimeSessionInvalidationReason, error: Error?) {
print(reason.rawValue)
}
func extendedRuntimeSessionDidStart(_ extendedRuntimeSession: WKExtendedRuntimeSession) {
print("did start")
}
func extendedRuntimeSessionWillExpire(_ extendedRuntimeSession: WKExtendedRuntimeSession) {
print("will expire")
}
}