How to create bindable custom objects in SWIFT? (conform with ObservableObject) - swift

Question

XCode Version 12.5 (12E262) - Swift 5
To simplify this example, I've created a testObj class and added a few items to an array.
Let's pretend that I want to render buttons on the screen (see preview below), once you click on the button, it should set testObj.isSelected = true which triggers the button to change the background color.
I know it's changing the value to true, however is not triggering the button to change its color.
Here's the example:
//
// TestView.swift
//
import Foundation
import SwiftUI
import Combine
struct TestView: View {
#State var arrayOfTestObj:[testObj] = [
testObj(label: "test1"),
testObj(label: "test2"),
testObj(label: "test3")
]
var body: some View {
VStack {
ForEach(arrayOfTestObj, id: \.id) { o in
HStack {
Text(o.label)
.width(200)
.padding(20)
.background(Color.red.opacity(o.isSelected ? 0.4: 0.1))
.onTapGesture {
o.isSelected.toggle()
}
}
}
}
}
}
class testObj: ObservableObject {
let didChange = PassthroughSubject<testObj, Never>()
var id:String = UUID().uuidString {didSet {didChange.send((self))}}
var label:String = "" {didSet {didChange.send((self))}}
var value:String = "" {didSet {didChange.send((self))}}
var isSelected:Bool = false {didSet {didChange.send((self))}}
init (label:String? = "") {
self.label = label!
}
}
struct TestView_Previews: PreviewProvider {
static var previews: some View {
TestView()
}
}
If I update the ForEach as...
ForEach($arrayOfTestObj, id: \.id) { o in
... then I get this error:
Key path value type '_' cannot be converted to contextual type '_'
How can I change testObj to make it bindable?
Any help is greatly appreciated.

Answer 1

struct TestView: View {
#State var arrayOfTestObj:[TestObj] = [
TestObj(label: "test1"),
TestObj(label: "test2"),
TestObj(label: "test3")
]
var body: some View {
VStack {
ForEach(arrayOfTestObj, id: \.id) { o in
//Use a row view
TestRowView(object: o)
}
}
}
}
//You can observe each object by creating a RowView
struct TestRowView: View {
//And by using this wrapper you observe changes
#ObservedObject var object: TestObj
var body: some View {
HStack {
Text(object.label)
.frame(width:200)
.padding(20)
.background(Color.red.opacity(object.isSelected ? 0.4: 0.1))
.onTapGesture {
object.isSelected.toggle()
}
}
}
}
//Classes and structs should start with a capital letter
class TestObj: ObservableObject {
//You don't have to declare didChange if you need to update manually use the built in objectDidChange
let id:String = UUID().uuidString
//#Published will notify of changes
#Published var label:String = ""
#Published var value:String = ""
#Published var isSelected:Bool = false
init (label:String? = "") {
self.label = label!
}
}
struct TestView_Previews: PreviewProvider {
static var previews: some View {
TestView()
}
}