SwiftUI Fetching contacts duplication

Question

I have a model view that has fetching contacts function:

class ContactsStore: ObservableObject {

@Published var contacts = [CNContact]()

func fetch() {} ...

And then in my View:

@EnvironmentObject var store: ContactsStore

var groupedContacts: [String: [CNContact]] {
    .init (
        grouping: store.contacts,
        by: {$0.nameFirstLetter}
    )
}
     ...
       List() {
            ForEach(self.groupedContacts.keys.sorted(), id: \.self) { key in ...

I've shortened my code for the convenience, will add/edit if needed. The issue I faced - every time my View is rendered the fetch function is called and my array of contacts is duplicated in my view. TIA for a help

UPD: Duplication happens due to method calling fetch in the List .onAppear. So I'm looking at how to call this method only once and not every time the View appears.

Aspid · Accepted Answer · 2020-03-22T11:51:47.647

You can do fetch in Init() like that:

struct someView: View{
    var list: [Settings]
    init(){
        let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
        let fetchRequest: NSFetchRequest<Settings> = Settings.fetchRequest()
        //... some order and filter if you need
        self.list = context.fetch(fetchRequest)
    }
    var body: some View{
        ...
        ForEach(list){settings in
            ...
        }
        ...
    }
}

Didn't try it with grouping, but you asked how to fetch only once. The answer is - in init().

But you cant get the @Environment in init, so i get the context from AppDelegate. Or you can pass the context as init parameter

SwiftUI Fetching contacts duplication

1 Answers1