SwiftUI 状态变量未更新

Question

I have a struct User with a list of hobbies as follows:

struct User: Hashable, Codable, Identifiable, Equatable {
    var id: String
    var name: String
    var hobbies: [String]
}

I then generate a list view using a list of users as a state variable. When the button in the list view is clicked a new hobby is added to a user's hobbies.

struct UsersListView: View {

    @State var users: [User]


    var body: some View {

                TitleView(titleText: "Friends")
                    .padding(.leading, 30.0)

                List(userDisplayList) { user in
                     Text(user.name)
                     Text(user.hobbies.joined(separator: ", "))
                     Button(action: {self.users[0].hobbies.append("new hobby")}
                }
            }
        }
    }
}

However, when I click on the button, the users state variable does not change and remains the same. Can anyone explain what is going on here?

Answer 1

You display every user in userDisplayList , not in users .

So when you change some value in users , SwiftUI think that there is nothing to update in your view, since nothing depends on users variable.

Try using List(users) { user in instead if there is no additional logic in your userDisplayList .

Answer 2

Try this:

    struct User: Hashable, Codable, Identifiable, Equatable {
    var id = UUID()
    var name: String
    var hobbies: [String]
}

struct UsersListView: View {

    @State var users: [User] = [User(name: "aaaa", hobbies: [])]


    var body: some View {

        List(users) { user in
                     Text(user.name)
                     Text(user.hobbies.joined(separator: ", "))
                        Button(action: {
                            self.users[0].hobbies.append("new hobby")
                        }) {
                            Text("Create hobby")
                        }

                }
            }
        }