SwiftUI Picker onReceive() called every time the body is rendered - swiftui

Question

i am using a Picker to show a segmented control and wish to know when the picker value changes so i can perform a non-UI action. Using the proposed onReceive() modifier (as suggested here) does not work as it is called every time the body is rendered.
Here's the code i have:
struct PickerView: View {
#State private var weather = 0
#State private var showMessage = false
var body: some View {
VStack(spacing: 24) {
Picker(selection: $weather, label: Text("Weather")) {
Image(systemName: "sun.max.fill").tag(0)
Image(systemName: "cloud.sun.rain.fill").tag(1)
}
.pickerStyle(SegmentedPickerStyle())
.frame(width: 120, height: 48)
.onReceive([weather].publisher.first()) { connectionType in
print("connection type is: \(connectionType)")
}
Button(action: { self.showMessage.toggle() }) {
Text("Press Me")
}
if showMessage {
Text("Hello World")
}
}
}
}
The onReceive() block will get called any time the body is rendered, including the first time and any time the button (which toggles showing a message) is pressed.
Any ideas why this is happening and how i can only react to when the picker value is changed?

Answer 1

Here is possible solution instead of .onReceive
Picker(selection: Binding( // << proxy binding
get: { self.weather },
set: { self.weather = $0
print("connection type is: \($0)") // side-effect
})
, label: Text("Weather")) {
Image(systemName: "sun.max.fill").tag(0)
Image(systemName: "cloud.sun.rain.fill").tag(1)
}