SwiftUI: How to cancel timer in SwiftUI view? - timer

Question

I am using a timer in a SwiftUI view as in code below. It works as expected BUT under some conditions I want to cancel/stop that timer. There seems to be no ".cancel" property or method on the timer var. How do I cancel this timer? Any ideas/tips?
import SwiftUI
struct ContentView: View {
#State private var selection = 2
#State private var rotation: Double = GBstrtest
let timer = Timer.publish (every: 0.8, on: .current, in: .common).autoconnect()
var body: some View {
TabView(selection: $selection){
Text("Settings")
.font(.title)
.tabItem {
VStack {
Image(systemName: "gear")
.font(Font.system(.title ))
Text("Settings")
}
}
.tag(0)
VStack {
Divider().padding(2)
ZStack {
Image("image1")
.resizable()
.aspectRatio(contentMode: .fit)
Image("image2")
.resizable()
.aspectRatio(contentMode:.fit)
.rotationEffect(.degrees(rotation))
.animation(.easeInOut(duration: 0.3) )
.padding(EdgeInsets(top: 0, leading: 50, bottom: 0, trailing: 50))
}
Spacer()
}
.tabItem {
VStack {
Image(systemName: "speedometer")
.font(Font.system(.title ))
Text("Read Meter")
}
}
.tag(1)
}
.onReceive(timer) {
_ in self.rotation = Double.random(in: 0 ... 200)
// How do I cancel timer HERE!?
}
}
}

Answer 1

Inside your conditional statement, use the following code:
self.timer.upstream.connect().cancel()

Answer 2

Full cycle goes like this:
struct MySwiftUIView : View {
...
#State var timer = Timer.publish (every: 1, on: .current, in: .common).autoconnect()
#State var timeRemaining = -1
var body: some View {
ZStack {
// Underlying shapes etc as needed
Text("\(timeRemaining)").
.opacity(timeRemaining > 0 ? 1 : 0)
.onReceive(timer) { _ in
if self.timeRemaining < 0 {
// We don't need it when we start off
self.timer.upstream.connect().cancel()
return
}
if self.timeRemaining > 0 {
self.timeRemaining -= 1
} else {
self.timer.upstream.connect().cancel()
// Do the action on end of timer. Text would have been hidden by now
}
}
.onTapGesture { // Or any other event handler that should start countdown
self.timeRemaining = Int(delayValue)
self.timer = Timer.publish (every: 1, on: .current, in:
.common).autoconnect()
}
}
Voila! A reusable timer, use it as many times as you'd like!