swift - 如何使用绑定(bind)关联 Swift 枚举？

Question

我有一个接受绑定(bind)作为参数的 GroupView，因为我希望 GroupView 修改枚举中的数据。

有人能帮我完成这个吗？

import SwiftUI
struct ContentView: View {
    @ObservedObject var viewModel = ViewModel()
    var body: some View {
        VStack {
            GroupView(group: /* What do i put here? */)  // <----------------
        }
    }
}

struct GroupView: View {
    @Binding var group: Group
    var body: some View {
        Text("Hello World")
    }
}

class ViewModel : ObservableObject {
    @Published var instruction: Instruction!
    init() {
        instruction = .group(Group(groupTitle: "A Group struct"))
    }
}

enum Instruction {
    case group(Group)
}
struct Group { var groupTitle: String }

Answer 1

好吧，这肯定会奏效...但可能有更好的方法来解决您的问题。但没有人比你更能确定这一点。所以我只回答你关于如何传递绑定(bind)的问题。

struct ContentView: View {
    @ObservedObject var viewModel = ViewModel()
    var body: some View {

        VStack {
            GroupView(group: viewModel.groupBinding)
        }
    }
}

class ViewModel : ObservableObject {
    @Published var instruction: Instruction!

    init() {
        instruction = .group(Group(groupTitle: "A Group struct"))
    }

    var groupBinding: Binding<Group> {
        return Binding<Group>(get: {
            if case .group(let g) = self.instruction {
                return g
            } else {
                return Group(groupTitle: "")
            }
        }, set: {
            self.instruction = .group($0)
        })
    }
}