How to reuse a view in SwiftUI and fill it different data? - swift

Question

noob here.
So Im coding a basic To-Do App and I need the user to be able to edit a task he previously entered. To do this, I wish to reuse my AddTaskView in the following way: once I tap "Edit" on the Task, the AddTaskView form gets presented and populated with all the Tasks data and pressing "Save" actually updates the data, instead of adding a new Task.
Currently, my AddTaskView stores all the forms variables in #State variables which have a value by default, such as:
#State private var taskTitle : String = ""
How can I send the data to AddTaskView that is already available since the task already exists to be able to populate the appropiate fields? My understanding is I cant just set #State variables values from outside the view.
Current AddTaskView.swift
struct AddTaskView: View {
//CoreDatas managedObjectEnvironment
#StateObject var vm : viewModel
#Environment(\.managedObjectContext) var moc
#Environment(\.presentationMode) var presentationMode
var categories : FetchedResults<Category>
#State private var taskTitle : String = ""
#State private var taskPriority : String = "Low"
#State private var chosenCategory : String? = ""
#State private var taskDate : Date = Date()
let priorities = ["Low", "High"]
var body: some View {
NavigationView {
Form {
Section(header: Text("Task info")) {
TextField("Task title", text: $taskTitle)
}
Section {
DatePicker("Date", selection: $taskDate)
}
Section {
Picker(
selection: $taskPriority,
label: Text("Priority")
) {
ForEach(self.priorities, id: \.self) {
Text($0).tag($0)
}
}
}
Section {
Picker(
selection: $chosenCategory,
label: Text("Category")
) {
ForEach(self.categories, id: \.categoryName) { cat in
Text(cat.categoryName ?? "Unknown").tag(cat.id)
}
}
}
Section {
Button("Save") {
self.vm.addTask(moc: self.moc, title: self.taskTitle, date: self.taskDate, priority: self.taskPriority, chosenCategory: chosenCategory!)
self.presentationMode.wrappedValue.dismiss()
}
}
}
.navigationTitle("Add Task")
}
}
I want to call and present this AddTaskView from another view where I have all the task info. As far as I understand, I cant just present the view such as:
AddTaskView(taskTitle: aTitle, taskPriority: aPriority, etc)
Any pointers are welcomed. thanks!

Answer 1

You did not ask a small question. I am going to recommend you go through Apple's Introducing SwiftUI. It will give you the foundation to understand what is going on, however the TLDR is every time you change an #State var in a struct, you are getting an entirely new struct. The values in a struct are immutable, regardless of what var might imply, and you literally make a new struct and put it in the old one's place.
And to answer your question as to presenting the view struct, yes, that would work. So would AddTaskView() the way you have your struct set up, though it wouldn't show much. Go hit the tutorial. It is well worth the time.