I’m building a WatchOS companion app. In a View there’s a Slider that reads and writes value. This value is being communicated between iOS and WatchOS app.
struct ReadingView: View {
@EnvironmentObject var watcher: ViewModelWatch
var body: some View {
CompactSlider(value: $watcher.sliderValue, in: -1000...1000, step: 50, direction: .center) {
VStack {
Text("Compensation")
Text(String(format: "%.0fK", watcher.sliderValue))
}
}
.onChange(of: watcher.sliderValue) { newValue in
ViewModelWatch.shared.session.transferUserInfo(["compensationValue": newValue])
}
}
}
This is how my model looks like:
class ViewModelWatch : NSObject, WCSessionDelegate, ObservableObject {
static let shared = ViewModelWatch()
var session: WCSession = .default
@Published var sliderValue = 0.0
init(session: WCSession = .default){
self.session = session
super.init()
self.session.delegate = self
session.activate()
}
func session(_ session: WCSession, didReceiveUserInfo userInfo: [String : Any] = [:]) {
self.sliderValue = userInfo["compensationValue"] as? Double ?? 0.0
}
}
Steps and what’s happening:
-
Ran the apps on both iOS and WatchOS.
-
Sent "compensationValue" UserInfo from iOS app and received in
didReceiveUserInfo
in the Watch app, the Slider view in iOS app updates just fine. -
Sent "compensationValue" UserInfo from Watch app and received in
didReceiveUserInfo
in the iOS app, the Slider view in iOS app updates just fine.
Issue:
- Now when I repeat the 2nd step i.e., send "compensationValue" UserInfo from iOS app to Watch app, the
CompactSlider
doesn’t update.
It’s like once @Published var sliderValue = 0.0
is written by CompactSlider
, it doesn’t update views when updated by didReceiveUserInfo
.
2
Answers
Try to assign value on main queue, like
or make view model
MainActor
if deployment target version allowsAdd
private
to this lineIt will expose if there is an area in your code where you are not using the same instance.
You should only be using
ViewModelWatch.shared
so they can share information.Another call of
ViewModelWatch()
will be separate fromViewModelWatch.shared