holding the item to add changes to CoreData in SwiftUI - swift

Question

I am just want to add comments under any post and save it into CoreData, but how can I Know where am I, I don't know how to link this comment to the post I created in CoreData. I mean when I fetch data (posts) from CoreData, I want this comment to be under the correct post. look at the code, I just fill comments by normal string array. It is not dynamic and cannot be saved in CoreData as an array and retrieved to be under its post screen shot to imagine the problem
struct CommentSheetView: View{
#ObservedObject var keyboardResponder = KeyboardResponder()
// #State var showCommentsSheet : Bool
var mainV = MainView()
var del = Post()
#ObservedObject var delegate = ViewModel()
var body: some View{
Spacer()
VStack(alignment: .leading){
Spacer()
Form{
Section(header: Text("comments")){
}
ForEach(delegate.array,id :\.self) { comment in
Text(comment)
}
}.frame(height: 550)
// Spacer()
Text("Type your comment below . . .")
.font(Font.system(size: 10))
.foregroundColor(.gray)
HStack{
TextEditor(text: $delegate.comment)
.frame(width: 300, height: 100)
.shadow(radius: 10)
.border(Color.gray, width: 1)
.background(Color(.systemGray6))
Button(action: {
// delegate.comments.append("Hi")
//showCommentsSheet = false
// mainV.fc = delegate.comment
delegate.array.append(delegate.comment)
}){
Image(systemName: "paperplane.circle.fill")
.resizable()
.scaledToFit()
.clipShape(Circle())
.frame(width: 30, height: 100)
.border(Color.gray, width: /*#START_MENU_TOKEN#*/1/*#END_MENU_TOKEN#*/)
.background(Color(.systemGray6))
}
}
Spacer()
}.offset(y: -keyboardResponder.currentHeight*0.5).padding()
}
}