Passing a timer to a child view in SwiftUI

user_10404084 0
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In my top level view, I have declared a timer like so: 

Struct ContentView: View  {
    @State var timer = Timer.publish(every: 1, on: .main, in: 
     .common).autoconnect()

    var body: some View {
            ZStack {
                if self.timerMode == .warmup {
                    WarmupView(
                        timer: $timer
                    )
                if self.timerMode == .work {
                    WorkView(
                        timer: $timer
                    )
       }
    }
}

In a child view, I want to be able to access and update this timer, which will serve as the single source of truth. 

Struct WarmupView: View {
  @Binding var timer: Publishers.Autoconnect<Timer.TimerPublisher>
  @Binding var timeRemaining: Int

  var body: some View {
    VStack {
      Text("\(self.timeRemaining)").font(.system(size: 160))
                            .onReceive(self.timer) { _ in
                            if self.timeRemaining > 0 {
                                self.timeRemaining -= 1
                            }
                        }
    }
  }
}

The timer is publishing to the warmup view without issues, but when timerMode is updated to .work (which has nearly identical code) and the view changes, the timer stops publishing.

swiftui swift iphone ios
1 Answers

Simple as changing the type of your @Binding var timer in your WarmupView to Publishers.Autoconnect<Timer.TimerPublisher>. The .autoconnect() wraps the timer publisher in another publisher, which changes the type.

Here's a simplified version of your code:

struct ContentView: View  {
    let timer = Timer.publish(every: 1, on: .main, in: .common).autoconnect()
    @State var remaining = 100

    var body: some View {
        Text("\(remaining)")
            .font(.system(size: 160))
            .onReceive(timer) { _ in
                if self.remaining > 0 {
                    self.remaining -= 1
                }
            }
    }
}
user_106144030
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