SwiftUI 绑定到数组中的@ObservableObject

Question

How do I pass a bindable object into a view inside a ForEach loop?

Minimum reproducible code below.

class Person: Identifiable, ObservableObject {
    let id: UUID = UUID()
    @Published var healthy: Bool = true
}


class GroupOfPeople {
    let people: [Person] = [Person(), Person(), Person()]
}

public struct GroupListView: View {
    
    //MARK: Environment and StateObject properties
    
    //MARK: State and Binding properties
    
    //MARK: Other properties
    let group: GroupOfPeople = GroupOfPeople()
    
    //MARK: Body
    public var body: some View {
        ForEach(group.people) { person in
            //ERROR: Cannot find '$person' in scope
            PersonView(person: $person)
        }
    }
    
    //MARK: Init
    
}

public struct PersonView: View {
    
    //MARK: Environment and StateObject properties
    
    //MARK: State and Binding properties
    @Binding var person: Person
    //MARK: Other properties
    
    
    //MARK: Body
    public var body: some View {
        switch person.healthy {
        case true:
            Text("Healthy")
        case false:
            Text("Not Healthy")
        }
    }
    
    //MARK: Init
    init(person: Binding<Person>) {
        self._person = person
    }
}

The error I get is Cannot find '$person' in scope . I understand that the @Binding part of the variable is not in scope while the ForEach loop is executing. I'm looking for advice on a different pattern to accomplish @Binding objects to views in a List in SwiftUI.

Answer 1

The SwiftUI way would be something like this:

// struct instead of class
struct Person: Identifiable {
    let id: UUID = UUID()
    var healthy: Bool = true
}


// class publishing an array of Person
class GroupOfPeople: ObservableObject {
    @Published var people: [Person] = [
        Person(), Person(), Person()
    ]
}

struct GroupListView: View {
    
    // instantiating the class
    @StateObject var group: GroupOfPeople = GroupOfPeople()
    
    var body: some View {
        List {
            // now you can use the $ init of ForEach
            ForEach($group.people) { $person in
                PersonView(person: $person)
            }
        }
    }
}

struct PersonView: View {
    
    @Binding var person: Person

    var body: some View {
        HStack {
            // ternary instead of switch
            Text(person.healthy ? "Healthy" : "Not Healthy")
            Spacer()
            // Button to change, so Binding makes some sense :)
            Button("change") {
                person.healthy.toggle()
            }
        }
    }
}

Answer 2

You don't need Binding . You need ObservedObject .

Answer 3

for anyone still wondering... it looks like this has been added

.onContinuousHover(perform: { phase in
    switch phase {
    case .active(let location):
        print(location.x)
    case .ended:
        print("ended")
    }
})