I have a SwiftUI project with Core Data. The data model is a simple one-to-many and two primary views which each have a textfield at the top and a button to add a new item to the list view below. The first view is for the One side of the relation and the second for the Many. So, the NavigationLink in the first opens the second and passes the One object. Pretty standard stuff, it would seem. The methodology for creating the One works and the list below gets updated immediately when the managed object context saves the new item. But, the same type of methodology doesn't refresh the list for the Many side when viewing on a device, although it does work fine in the simulator and the preview window. The data is definitely saved because if you navigate back to the One side then re-select it to re-load the Many view, it shows the new item in the list.
I've looked through lots of tutorials, other questions, etc. and haven't found a reason for this. Am I doing something wrong in how I am going to the Many side of the relation, or is there something else I have to do to refresh the view only on the Many side? Thanks!!!
Full project available at https://github.com/fahrsoft/OneToManyTest
From the ContentView, showing the One side (note: OneView is a simple view that takes the object and shows the text. Same for ManyView.):
struct ContentView: View {
@Environment(\.managedObjectContext) var moc
@FetchRequest(entity: One.entity(), sortDescriptors: []) var ones: FetchedResults<One>
@State private var newName = ""
@State var isNavTitleHidden = true
var body: some View {
NavigationView {
VStack {
HStack {
TextField("New One", text: self.$newName)
Spacer()
Button(action: {
let newOne = One(context: self.moc)
newOne.name = self.newName
self.newName = ""
try? self.moc.save()
}) {
Image(systemName: "plus.circle.fill")
.foregroundColor(.green)
.frame(width: 32, height: 32, alignment: .center)
}
}
.padding(.top)
.padding(.horizontal)
List {
Section(header: Text("Ones")) {
ForEach(self.ones, id:\.self) { (one:One) in
NavigationLink(destination: OneDetailView(one: one, isNavTitleHidden: self.$isNavTitleHidden).environment(\.managedObjectContext, self.moc)) {
OneView(one: one).environment(\.managedObjectContext, self.moc)
}
}
.onDelete { indexSet in
let deleteOne = self.ones[indexSet.first!]
self.moc.delete(deleteOne)
do {
try self.moc.save()
} catch {
print(error)
}
}
}
}
}
.navigationBarTitle(Text("Ones List"))
.navigationBarHidden(self.isNavTitleHidden)
.onAppear {
self.isNavTitleHidden = true
}
}
}}
From the OneDetailView showing the Many side:
struct OneDetailView: View {
@Environment(\.managedObjectContext) var moc
@ObservedObject var one: One
@State private var newManyAttribute = ""
@Binding var isNavTitleHidden: Bool
var body: some View {
VStack {
HStack {
TextField("New Many", text: self.$newManyAttribute)
Spacer()
Button(action: {
let newMany = Many(context: self.moc)
newMany.attribute = self.newManyAttribute
self.newManyAttribute = ""
self.one.addToMany(newMany)
try? self.moc.save()
}) {
Image(systemName: "plus.circle.fill")
.foregroundColor(.green)
.frame(width: 32, height: 32, alignment: .center)
}
}
.padding(.top)
.padding(.horizontal)
List {
Section(header: Text("Manys")) {
ForEach(self.one.manyArray, id: \.self) { many in
ManyView(many: many).environment(\.managedObjectContext, self.moc)
}
}
}
}
.navigationBarTitle("\(self.one.wrappedName) Details")
.onAppear {
self.isNavTitleHidden = false
}
}}