SwiftUI ForEach Bindable List errors

Question

I would appreciate help with SwiftUI bindable lists. I read the following article and tried it on my app but I'm getting errors. https://www.swiftbysundell.com/articles/bindable-swiftui-list-elements/

First, the following View including the non-bindable ordinary ForEach list works fine without any errors

@ObservedObject var notificationsViewModel = NotificationsViewModel.shared
//NotificationsViewModel does a API call and puts the fetched data in the Notifications Model


var body: some View {

VStack {
ForEach(notificationsViewModel.notifications?.notificationsDetails ?? [NotificationsDetail]()) { notificationsDetail in 
---additional code here--- }
}

Model below:

struct Notifications: Codable, Identifiable {
    
    let id = UUID()
    let numberOfNotifications: Int
    var notificationsDetails: [NotificationsDetail]

        enum CodingKeys: String, CodingKey {
            case numberOfNotifications = "number_of_notifications"
            case notificationsDetails = "notifications"
        }
}

struct NotificationsDetail: Codable, Identifiable, Equatable {
    let id: Int
    let notificationsCategoriesId: Int
    let questionsUsersName: String?
  
    enum CodingKeys: String, CodingKey {
        case id = "notifications_id"
        case notificationsCategoriesId = "notifications_categories_id"
        case questionsUsersName = "questions_users_name"
        
    }
}

When I try to change this ForEach to a bindable one, I start getting multiple errors.

ForEach($notificationsViewModel.notifications?.notificationsDetails ?? [NotificationsDetail]()) { $notificationsDetail in 
---additional code here using $notificationsDetail---}

When I try to fix some of the errors such as "remove ?", I get a new error saying I need to add the ?.

When I delete the default value ?? NotificationsDetail, I still get errors

The Xcode build version is iOS15.

Does anyone know how to fix this? Thanks in advance.

jrturton · Accepted Answer · 2022-04-04 08:33:15Z

2

ForEach($notificationsViewModel.notifications?.notificationsDetails ?? [NotificationsDetail]()

Is confusing the type system, because one side of the ?? is a binding to an array of values, and the other side is an array of values. There's also an optional in your key path to make things more complicated.

Try to rearrange the NotificationsViewModel type so that it just surfaces a non-optional array instead of having all this optional mess at the view level. Is it really meaningful to have an optional notification property, or can an empty one be used instead? Do you need the separate notifications struct? Are you just modelling your data types directly from API responses? Perhaps you can make changes to your model types to make them easier to work with?

answered Apr 4, 2022 at 8:33

jrturton

119k33 gold badges256 silver badges274 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Hiro Over a year ago

Hi jrturton. I made the notification property non-optional, and then it worked! Thanks for saving my week!!

Collectives™ on Stack Overflow

SwiftUI ForEach Bindable List errors

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related