@FetchRequest predicate not updating when UserDefaults value changes SwiftUI-CodePudding

I'm having trouble figuring out how to make a SwiftUI @FetchRequest use a predicate only if a Boolean value stored in UserDefaults is true .

The issue is that the FetchedResults is not changing when the value for showAvailable changes. Currently I have to relaunch the app to see the showAvailable value based results.

struct ContentView: View {

@AppStorage("showAvailable") private var showAvailable : Bool = false


@FetchRequest private var list: FetchedResults<Item>



init() {
        @AppStorage("showAvailable") var showAvailable : Bool = false
        _list = FetchRequest(
            sortDescriptors: [],
            predicate: showAvailable ? NSPredicate(format: "parent == nil") : nil,
            animation: .default
        )
}

var body: some View {
     Button("Cancel") {
        showAvailable.toggle()
     }
}

CodePudding user response：

I would update the fetch request with a new predicate in the Button action and that update should trigger the request to be executed again

struct ContentView: View {
    @AppStorage("showAvailable") private var showAvailable : Bool = false

    @FetchRequest(sortDescriptors: [], 
                  predicate: NSPredicate(value: true)
                  animation: .default)
    private var list: FetchedResults<Item>

    var body: some View {
        Button("Cancel") {
            showAvailable.toggle()
            updatePredicate()
        }
        .onAppear {
            updatePredicate()
        }
    }

    private func updatePredicate() {
        if showAvailable {
            list.nspredicate = NSPredicate(format: "parent == nil")
        } else {
            list.nspredicate = NSPredicate(value: true)
        }        
    }
}