Using EnvironmentObject to update existing list - list

Question

I have an existing list, but I want to be able to add new items to it. Right now, I am using #EnvironmentObject, but when I add an element to the array, the view is not updated? I've seen solutions on the internet where you use objectWillChange.send(), but as a beginner in Swift, I don't know how to manipulate it to do what I want.
Class
class ChecklistObject: ObservableObject {
#Published var description: String
#Published var complete: Bool
let ID: Int
init(_ desc: String, _ complete: Bool, ID: Int){
description = desc
self.complete = complete
self.ID = ID
}
}
class Event: ObservableObject {
#Published var Name: String
#Published var CalendarID: Int
var timeStart: Date
var timeEnd: Date
#Published var checklist = [ChecklistObject]()
#Published var checklistSize = 0
init(_ eventName: String, _ calID: Int, _ timeStart: Date, _ timeEnd: Date) {
Name = eventName
CalendarID = calID
self.timeStart = timeStart
self.timeEnd = timeEnd
logger.log("Successfully created new event")
}
func newChecklistItem(Content: String){
objectWillChange.send()
checklist.append(ChecklistObject(Content, false, ID: getChecklistSize()))
//checklistSize = checklistSize + 1
}
func getChecklistSize() -> Int {
return checklist.count
}
}
List
VStack (alignment: .leading) {
Text("Checklist")
.font(.title)
.bold()
ForEach(event.checklist.indices) { idx in
ChecklistDisplayRow()
.environmentObject(event.checklist[idx])
}
Spacer()
.frame(width: 360, height: 10)
Button(action: {
event.newChecklistItem(Content: "New item")
event.checklistSize = event.checklistSize + 1
}) {
HStack{
if #available(OSX 11.0, *) {
Image(systemName: "plus.circle")
} else {
Path{ path in
path.move(to: CGPoint(x: 10, y: 20))
path.addLine(to: CGPoint(x: 10, y:0))
path.move(to:CGPoint(x: 0, y: 10))
path.addLine(to: CGPoint(x: 20, y: 10))
}
}
Text("Add new item")
.font(.caption)
}
}
.buttonStyle(PlainButtonStyle())
}
Thanks in advance.

Answer 1

It's because of the version of ForEach that you are using. This version:
init(_ data: Range<Int>, content: #escaping (Int) -> Content)
"only reads the initial value of the provided data and doesn’t need to identify views across updates." (Apple's docs)
To get dynamic updating, you need to use one of the other forms of ForEach.
ForEach(event.checklist, id: \.ID) { item in
ChecklistDisplayRow()
.environmentObject(item)
}
You could even change the ID property of your ChecklistObject to id and then add Identifiable conformance.
ForEach(event.checklist) { item in
ChecklistDisplayRow()
.environmentObject(item)
}
(And though it's hard to say since we don't see the rest of your code, but does the item really need to be passed in as an EnvironmentObject or could it be done in the initializer for ChecklistDisplayRow?)