Deselecting item from a picker SwiftUI - swift

Question

I use a form with a picker, and everything works fine (I am able to select an element from the picker), but I cannot deselect it. Does there exist a way to deselect an item from the picker?
Thank you!
Picker(selection: $model.countries, label: Text("country")) {
ForEach(model.countries, id: \.self) { country in
Text(country!.name)
.tag(country)
}
}

Answer 1

To deselect we need optional storage for picker value, so here is a demo of possible approach.
Tested with Xcode 12.1 / iOS 14.1
struct ContentView: View {
#State private var value: Int?
var body: some View {
NavigationView {
Form {
let selected = Binding(
get: { self.value },
set: { self.value = $0 == self.value ? nil : $0 }
)
Picker("Select", selection: selected) {
ForEach(0...9, id: \.self) {
Text("\($0)").tag(Optional($0))
}
}
}
}
}
}

Answer 2

I learned almost all I know about SwiftUI Bindings (with Core Data) by reading this blog by Jim Dovey. The remainder is a combination of some research and many hours of making mistakes.
So when I combine Jim's technique to create Extensions on SwiftUI Binding with Asperi's answer, then we end up with something like this...
public extension Binding where Value: Equatable {
init(_ source: Binding<Value>, deselectTo value: Value) {
self.init(get: { source.wrappedValue },
set: { source.wrappedValue = $0 == source.wrappedValue ? value : $0 }
)
}
}
Which can then be used throughout your code like this...
Picker("country", selection: Binding($selection, deselectTo: nil)) { ... }
OR
Picker("country", selection: Binding($selection, deselectTo: someOtherValue)) { ... }

Answer 3

First of, we can fix the selection. It should match the type of the tag. The tag is given Country, so to have a selection where nothing might be selected, we should use Country? as the selection type.
It should looks like this:
struct ContentView: View {
#ObservedObject private var model = Model()
#State private var selection: Country?
var body: some View {
NavigationView {
Form {
Picker(selection: $selection, label: Text("country")) {
ForEach(model.countries, id: \.self) { country in
Text(country!.name)
.tag(country)
}
}
Button("Clear") {
selection = nil
}
}
}
}
}
You then just need to set the selection to nil, which is done in the button. You could set selection to nil by any action you want.

Answer 4

If your deployment target is set to iOS 14 or higher -- Apple has provided a built-in onChange extension to View where you can deselect your row using tag, which can be used like this instead (Thanks)
Picker(selection: $favoriteColor, label: Text("Color")) {
// ..
}
.onChange(of: favoriteColor) { print("Color tag: \($0)") }