Problems with timer and views in SwiftUI - swiftui

Question

I try to develop an WatchOS app, where the views are feeded by a timer:
import SwiftUI
import Combine
class AcidityTimer: ObservableObject {
#Published var num: Int = 0
private var subscription: AnyCancellable?
init() {
Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { _ in
self.num += 1
if self.num == 101 {
self.num = 0
}
}
}
}
struct AcidityTextView: View {
#EnvironmentObject var acTimer: AcidityTimer
#State var acidity: Double = 0.0
var body: some View {
Text(String(format: "Acidity: %.1f", acidity))
.onReceive(acTimer.$num) { result in
acidity = Double(result) / 10.0
}
}
}
struct AcidityGaugeView: View {
#State var acidity = 0.0
#EnvironmentObject var acTimer: AcidityTimer
var body: some View {
Gauge(value: acidity, in: 0...10) {
Image(systemName: "drop.fill")
.foregroundColor(.green)
} currentValueLabel: {
Text("\(acidity, specifier: "%.1f")")
} minimumValueLabel: {
Text("0")
} maximumValueLabel: {
Text("10")
}
.gaugeStyle(CircularGaugeStyle())
.onReceive(acTimer.$num) { result in
acidity = Double(result) / 10.0
}
}
}
struct ContentView: View {
#ObservedObject var acTimer = AcidityTimer()
#State var counter: Int = 0
var body: some View {
TabView {
AcidityTextView()
.environmentObject(acTimer)
AcidityGaugeView()
.environmentObject(acTimer)
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
The app itself runs fine on the Apple Watch simulator, but I get the error message:
[SwiftUI] Accessing State's value outside of being installed on a View. This will result in a constant Binding of the initial value and will not update.
Any idea what's wrong?

Answer 1

You use timer on initial and nowhere didn't stopped or update
You can change implementation to
struct ContentView: View {
#State var timeRemaining = 10
let timer = Timer.publish(every: 1, on: .main, in: .common).autoconnect()
var body: some View {
Text("\(timeRemaining)")
.onReceive(timer) { _ in
if timeRemaining > 0 {
timeRemaining -= 1
}
}
}
}