NavigationLink is activated automatically - core-data

Question

I have the following code inside a CoreData SwiftUI project:
import SwiftUI
struct ContentView: View {
#FetchRequest(entity: TestObject.entity(), sortDescriptors: [NSSortDescriptor(keyPath: \TestObject.name, ascending: true)]) var objects: FetchedResults<TestObject>
#Environment(\.managedObjectContext) var managedObjectContext
#State private var showFavorites = true
var body: some View {
NavigationView {
List {
if(showFavorites) {
Section(header: Text("Favorites").font(.headline).padding(.leading, -8)) {
ForEach(self.objects.filter({ (testObj) -> Bool in
return testObj.isFavorite
}), id: \.id) { obj in
NavigationLink(destination: DetailsView(testObject: obj)) {
Text(obj.name ?? "")
}
}
}
}
Section(header: Text("All").font(.headline).padding(.leading, -8)) {
ForEach(self.objects, id: \.id) { obj in
NavigationLink(destination: DetailsView(testObject: obj)) {
Text(obj.name ?? "")
}
}
}
}.listStyle(GroupedListStyle())
.environment(\.horizontalSizeClass, .regular)
.navigationBarTitle("Test", displayMode: .large)
.navigationBarItems(
trailing: Button(action: {
let newObj = TestObject(context: self.managedObjectContext)
newObj.name = "newTest"
newObj.id = UUID()
newObj.isFavorite = false
do {
try self.managedObjectContext.save()
} catch let error {
print(error)
print("error saving object")
}
}) {
Image(systemName: "plus")
}
)
}
}
}
struct DetailsView : View{
#ObservedObject var testObject : TestObject
var body : some View {
VStack {
Text(testObject.name ?? "")
}.navigationBarTitle("Detail")
.navigationBarItems(
trailing: HStack {
Button(action: {
self.testObject.isFavorite.toggle()
}) {
Image(systemName: self.testObject.isFavorite ? "heart.fill" : "heart")
}
}
)
}
}
And this entity in the xcdatamodeld file:
If i start the app for the first time, i can add new TestObjects via a tap on the plus image in the NavigationBar, which then get added to the list. If i then tap on one of the objects, i navigate to the DetailsView. On this View, tapping the NavigationBarButton with the heart should mark the object as favorite so that if the user navigates back, this is also displayed in the first part if the list, the favorites. It works so far, but i have this weird effect:
Video on Imgur
It looks like the NavigationLink for the extra element in the favorites section is automatically triggered. Any idea how i can fix this?
Thanks in advance

Answer 1

Try the following (cannot test your code, so just an idea)
struct DetailsView : View {
#ObservedObject var testObject : TestObject
#State private var isFavorite: Bool
init(testObject: TestObject) {
self.testObject = testObject
_isFavorite = State(initialValue: testObject.isFavorite)
}
var body : some View {
VStack {
Text(testObject.name ?? "")
}.navigationBarTitle("Detail")
.navigationBarItems(
trailing: HStack {
Button(action: {
self.isFavorite.toggle()
}) {
Image(systemName: self.isFavorite ? "heart.fill" : "heart")
}
}
)
.onDisappear {
DispatchQueue.main.async { // << this might be redundant, try w/ and w/o
self.testObject.isFavorite = self.isFavorite
}
}
}
}