How do you bind a list view - arrays

Question

I have a CoordinateList view that shows a list of CoordinateRow views that have been entered, and are editable in place (in the list view). To add a new point to the list, the user presses a button at the bottom of the list, and it adds a row (without going to another screen). How do I make it update the view to show this new entry? I have tried wrapping the append function of the list of coordinates with a function so that I can call objectWillChange.send() when adding to the list, but it doesn't seem to do anything.
I guess I don't have enough reputation to upload an image, but here's an image:
import SwiftUI
class LocationTime : ObservableObject {
#Published var lat: String = "0.0"
#Published var lon: String = "0.0"
#Published var timestamp: String = "SomeDateTime"
}
class ModelData: ObservableObject {
#Published var positionCoords = [LocationTime]()
func appendPosition(_ loc: LocationTime) {
objectWillChange.send()
positionCoords.append(loc)
}
}
struct CoordinateRow: View {
#EnvironmentObject var modelData: ModelData
var pointIndex : Int
var body: some View {
HStack {
Text("Lon: ")
TextField("40",text:$modelData.positionCoords[pointIndex].lon)
Text("Lat: ")
TextField("",text:$modelData.positionCoords[pointIndex].lat)
Text("Time: ")
TextField("time",text:$modelData.positionCoords[pointIndex].timestamp)
}.padding()
.overlay(RoundedRectangle(cornerRadius:16)
.stroke(Color.blue,lineWidth:4.0))
}
}
struct CoordinateList: View {
#EnvironmentObject var modelData : ModelData
var body: some View {
VStack{
Text("Location Log")
.font(.largeTitle).padding()
List{
ForEach(modelData.positionCoords.indices){
CoordinateRow(pointIndex: $0).environmentObject(modelData)
}
}
Button(action:{
modelData.appendPosition(LocationTime())
print(modelData.positionCoords.count)
}){
Image(systemName: "plus.circle")
.imageScale(.large)
.scaleEffect(2.0)
.padding()
}
Spacer()
}
}
}

Answer 1

You need identify records in ForEach
ForEach(modelData.positionCoords.indices, id: \.self){ // << here !!
CoordinateRow(pointIndex: $0).environmentObject(modelData)
}
and by the way, remove objectWillChange.send()
func appendPosition(_ loc: LocationTime) {
// objectWillChange.send() // << called automatically for #Published
positionCoords.append(loc)
}