Stop a timer on an if statement within a view - swift

Question

I'am quite new to Swift and I despair of a problem.
I created a class with two functions to start and stop a timer.
There's a struct that starts the timer (start function) with onAppear.
Within the struct there's a button to stop the time.
import SwiftUI
class StopWatch: ObservableObject {
#Published var secondsElapsed = 0.0
var timer = Timer()
func startTimer() {
timer = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { timer in
self.secondsElapsed += 0.1 }
}
func stopTimer() {
timer.invalidate()
}
}
struct Test: View {
#ObservedObject var stopWatch = StopWatch()
var body: some View {
VStack{
Button("Stop") {
stopWatch.stopTimer()
}
Text(String(format: "%.1f", self.stopWatch.secondsElapsed))
}.onAppear(perform: {stopWatch.startTimer()})
}
}
The timer starts if the view starts. So far so good :-).
But I want to get rid of the stop button and replace it with an if statement like:
if stopWatch.secondsElapsed > 5.0 {
stopWatch.stopTimer() }
I want to stop the timer without a user action by this if statement and the current timer value should show up.
I tried for hours, but I didn't get it. For that case I get the error message "Type '()' cannot conform to 'View'", but I tried a lot of other things and got a lot of other errors.
Can anyone help me?

Answer 1

If you want the timer to stop on 5 seconds you should probably do this in the closure from the timer. You can do this:
func startTimer() {
timer = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { timer in
self.secondsElapsed += 0.1
if self.secondselapsed == 5.0 {
timer.invalidate()
}
}
}
You get this error ("Type '()' cannot conform to 'View'") because you try to execute code within the body of a SwiftUI view without returning a view. If you really want to do this in the body for some reason you could do it like this: (I would not recommend doing this)
if stopWatch.secondsElapsed > 5.0 {
Text("Five seconds elapsed")
.onAppear {
stopWatch.stop()
}
}