removing from array is not calling set

Question

I have a list

List {
    ForEach (appState.foo.indices, id: \.self) { fooIndex in
        Text(foo[fooIndex].name)
    }
    .onDelete(perform: self.deleteRow)
}

with a function that deletes a row from the foo array:

private func deleteRow(at indexSet: IndexSet) {
    self.appState.foo.remove(atOffsets: indexSet)
}

and an observable object that acts as an environment object in the view with the list:

class AppState: ObservableObject {

    var foo: [Bar] {
        set {
            if let encoded = try? JSONEncoder().encode(newValue) {
            let defaults = UserDefaults.standard
                 defaults.set(encoded, forKey: "foo")
            }
            objectWillChange.send()
            self.myFunc()
        }
        get {
            if let savedTrainings = UserDefaults.standard.object(forKey: "trainings") as? Data,
                let loadedTraining = try? JSONDecoder().decode([Training].self, from: savedTrainings) {
                return loadedTraining
            }
            return []
        }
    }
// ....
    func myFunc() {
        print("I'm not printing when you delete a row")
    }
}

How can I get my myFunc() triggered when I delete a row?

Frankenstein · Accepted Answer · 2020-06-02 06:56:40Z

1

Use stored property instead of a computed property. To fix your issue modify the foo property in AppState like this:

struct Bar: Encodable { }

class AppState: ObservableObject {
    var foo: [Bar] {
        didSet {
            if let encoded = try? JSONEncoder().encode(foo) {
                 UserDefaults.standard.set(encoded, forKey: "foo")
            }
            objectWillChange.send()
            myFunc()
        }
    }
    init() {
        if let data = UserDefaults.standard.data(forKey: "foo"),
            let savedFoo = try? JSONDecoder().decode([Bar].self, from: data) {
            foo = savedFoo
        } else {
            foo = []
        }
    }
    func myFunc() {
        print("I'm not printing when you delete a row")
    }
}

edited Jun 2, 2020 at 6:56

answered Jun 2, 2020 at 6:01

Frankenstein

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4 Comments

T. Karter Over a year ago

Didn't know that this information was important: Within the setter I am saving the foo array to the user defaults. Thus I need the setter and you can't use didSet together with a setter

Frankenstein Over a year ago

You can use didSet instead of set for that purpose. Just use foo instead of newValue.

T. Karter Over a year ago

Now I just need a solution for my getter that can't be use together with didSet.

Frankenstein Over a year ago

Do the getting part in init. Check the init.

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