Background of button not conditionally rendering - swift

Question

Essentially I have a button when pressed I want the background to become a different color. In order to do this I have an object that I alter, I have printed out the value of the Bool value in the object and see its changing but the color of the button is not changing.
Object With Bool:
class dummyObject: Identifiable, ObservableObject {
let objectWillChange = ObservableObjectPublisher()
var id = UUID()
var isSelected: Bool {
willSet {
objectWillChange.send()
}
}
init(isSelected:Bool) {
self.isSelected = isSelected
}
}
View:
struct SelectionView: View {
var objs: [dummyObject] = [
dummyObject.init(isSelected: false)
]
var body: some View {
HStack{
ForEach(objs) { obj in
Button(action: {
obj.isSelected.toggle()
print("\(obj.isSelected)")
}) {
VStack {
Text("Test")
.foregroundColor(obj.isSelected ? Color.white : Color.gray)
.font(.caption)
}
}.frame(width:55,height: 55)
.padding()
.background(obj.isSelected ? Color.red : Color.white)
.padding(.horizontal, 3)
.clipShape(Circle()).shadow(radius: 6)
}
}.frame(minWidth: 0, maxWidth: .infinity)
.padding()
}
}

Answer 1

Extract your Button into other view, where obj is #ObservedObject and everything will work:
import SwiftUI
import Combine
class dummyObject: Identifiable, ObservableObject {
let objectWillChange = ObservableObjectPublisher()
var id = UUID()
var isSelected: Bool {
willSet {
objectWillChange.send()
}
}
init(isSelected:Bool) {
self.isSelected = isSelected
}
}
struct SelectionView: View {
var objs: [dummyObject] = [dummyObject.init(isSelected: false)]
var body: some View {
HStack{
ForEach(objs) { obj in
ObjectButton(obj: obj)
}
}
}
}
struct ObjectButton: View {
#ObservedObject var obj: dummyObject
var body: some View {
Button(action: {
self.obj.isSelected.toggle()
print("\(self.obj.isSelected)")
}) {
VStack {
Text("Test")
.foregroundColor(obj.isSelected ? Color.white : Color.gray)
.font(.caption)
}
}.frame(width:55,height: 55)
.padding()
.background(obj.isSelected ? Color.red : Color.white)
.padding(.horizontal, 3)
.clipShape(Circle()).shadow(radius: 6)
}
}
struct SelectionView_Previews: PreviewProvider {
static var previews: some View {
SelectionView()
}
}

Answer 2

Here is modified your snapshot of code that works. Tested with Xcode 11.2 / iOS 13.2.
The main idea is made a model as value-type, so modifications of properties modify model itself, and introducing #State for view would refresh on changes.
struct dummyObject: Identifiable, Hashable {
var id = UUID()
var isSelected: Bool
}
struct SelectionView: View {
#State var objs: [dummyObject] = [
dummyObject(isSelected: false)
]
var body: some View {
HStack{
ForEach(Array(objs.enumerated()), id: \.element) { (i, _) in
Button(action: {
self.objs[i].isSelected.toggle()
print("\(self.objs[i].isSelected)")
}) {
VStack {
Text("Test")
.foregroundColor(self.objs[i].isSelected ? Color.white : Color.gray)
.font(.caption)
}
}.frame(width:55,height: 55)
.padding()
.background(self.objs[i].isSelected ? Color.red : Color.white)
.padding(.horizontal, 3)
.clipShape(Circle()).shadow(radius: 6)
}
}.frame(minWidth: 0, maxWidth: .infinity)
.padding()
}
}