Change (toggle) property on passed object [closed] - swiftui

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I'm clearly not understanding this in SwiftUI.
I have a task struct with several properties one of which - 'isHotList' is a Boolean that I want to be able to toggle on and off.
I created a row view for each task and then use this to populate a list view for all the tasks loaded from JSON - no problems there. Moved on and added a detail view (which takes a task object passed in from the list view) with a toggle button for the isHotList the problem is that the toggle works correctly in the detail view but doesn't carry back to the list view .... ?
I suspect I've created two seperate instances of the task but I'm not sure. I've used #State to declare the task but I can't get #Binding to work correctly for me.
Toggle in the detail view, task is declared with #State in this view file ...
Button(action: {
task.isHotList.toggle()
print(task.isHotList)
}){
Image(systemName: "flame.fill")
.foregroundColor(task.isHotList ? Color.orange : Color.gray)
}
The list view (separate file)
ForEach(filteredHotTasks) { task in
NavigationLink(destination: TaskDetail(task: task)) {
TaskRow(task: task)
}
}
I'm really trying to learn here but this has me confused as to what is / isn't going on
As requested the full detail view file
struct TaskDetail: View {
#EnvironmentObject var modelData: ModelData
#State var task: Task
var taskIndex: Int {
modelData.tasks.firstIndex(where: {$0.id == task.id})!
}
var body: some View {
ScrollView {
VStack(alignment: .leading) {
HStack {
Text(task.title)
.font(.title2)
.padding(.bottom, 10)
Spacer()
Button(action: {
task.isHotList.toggle()
print(task.isHotList)
}){
Image(systemName: "flame.fill")
.foregroundColor(task.isHotList ? Color.orange : Color.gray)
}
}
HStack {
Text(task.category)
.font(.subheadline)
Spacer()
HStack {
Image(systemName: "calendar.badge.clock")
Text(task.dueDate)
.font(.subheadline)
}
}
}
.padding()
}
}
}

Answer 1

Remove #State
struct TaskDetail: View {
#EnvironmentObject var modelData: ModelData
var task: Task /* NEW */
var taskIndex: Int {
modelData.tasks.firstIndex(where: {$0.id == task.id})!
}
}
And use
Button(action: {
/* filteredHotTasks is the array that contains tasks. */
modelData.filteredHotTasks[taskIndex].isHotList.toggle()
print(task.isHotList)
})
Remember to pass modelData using .environmentObject(modelData) somwhere in one of your root views.
If you do not do, use #ObservedObject instead of #EnvironmentObject.
struct TaskDetail: View {
#ObservedObject var modelData: ModelData /* NEW */
var task: Task /* NEW */
var taskIndex: Int {
modelData.tasks.firstIndex(where: {$0.id == task.id})!
}
}
And
NavigationLink(destination: TaskDetail(modelData: modelData, task: task)) {
TaskRow(task: task)
}
Have a look at my answer to this question
Declaring TextField and Toggle in a SwiftUI dynamic form
For more info, read this article.
Managing Model Data in Your App
🎁
Confirm Task to Equatable in addition to the rest of the protocols you confirm to.
struct Task: Codable, Identifiable, Equatable {
}
Doing so you avoid using task.id whenever you want to know if two tasks are equal as in the firstIndex
var taskIndex: Int {
modelData.tasks.firstIndex(where: {$0 == task})!
}