Using Negative Values in a SwifUI PrgressView Outside the Parent View - swiftui

Question

I ca use negative values in a SwifUI PrgressView within the parent view, which changes the
progress bar into an indeterminate view, but I cannot make the value negative from outside the
parent view. Why? I have no problem passing the value, but the ProgressView hiccups when I try
to used the passed value.
I have been playing around with the SwiftUI ProgressView in hopes of finding a
nice trick to turn an indeterminate view on & off programatically. I found
that if I create a determinate view with a negative (out of range) number, it
becomes an indeterminate view, all be it with a warning that the value is out
of range - But it works! The following code snipit shows this:
struct ContentView: View {
var body: some View {
ProgressView("Value is 0.5: ", value: 0.5)
.padding()
ProgressView("Value is -0.5: ", value: -0.5)
.padding()
}
}
If I try to set the value outside the ProgressView(), as follows, all is still
good, though the warning remains:
struct ContentView: View {
#State var negativeValue = -0.5
var body: some View {
ProgressView("Value is 0.5: ", value: 0.5)
.padding()
ProgressView("Value is -0.5: ", value: negativeValue)
.padding()
}
}
However, if I try to change the value from somewhere outside the parent struct, as shown below, it compiles but won't change values & gives the error message "[SwiftUI] ProgressView
initialized with an out-of-bounds progress value. The value will be clamped to the range of
0...total." Yet it was willing to use the negative value in the 1st 2 examples.
struct ContentView: View {
#State var negativeValue = 0.75
var body: some View {
ProgressView("Value is 0.5: ", value: 0.5)
.padding()
ProgressView("Value is -0.5: ", value: negativeValue)
.padding()
Button("Change Value") {
ExtStruct.doChange()
negativeValue = ExtStruct.newValue
}
}
}
struct ExtStruct {
static var newValue = 0.0
static func doChange() {newValue = -0.5}
}
I have used this trick before with other views, such as Text(), but it does not
seem to work with ProgressView. These examples were set up in Xcode Version 14.1
(14B47b) but showed the same behavior before upgrading. There are other ways of achieving
what I need but this seems so simple. What am I missing?