SwiftUI报错：无法将Published.Publisher转为Binding类型的解决方案咨询

问题场景 #

我在构建SwiftUI项目时遇到结构问题，代码无法正常运行：

class Parent : Codable, ObservableObject {
    @Published public var children: [Child]?

    public func getChildren(with name: String) -> [Child] {
        return children?.filter { $0.name == name } ?? []
    }
}

class Child : Codable, Hashable, ObservableObject {
    static func == (lhs: Child, rhs: Child) -> Bool {
        return lhs.name == rhs.name && lhs.isSomething == rhs.isSomething
    }

    func hash(into hasher: inout Hasher) {
        hasher.combine(name)
        hasher.combine(isSomething)
    }

    let name: String
    @Published var isSomething: Bool
}

...

struct MyView : View {
    @ObservedObject var parent: Parent
    var names: [String]

    var body: some View {
        ForEach(names, id: \.self) { name in

            ...

            ForEach(parent.getChildren(with: name), id: \.self) { child in
                Toggle(isOn: child.$isSomething) { // <== 错误位置
                    ...
                }
            }
        }
    }
}

Toggle组件处出现报错：Cannot convert value of type 'Published<>.Publisher' to expected argument type 'Binding<>'。尝试Toggle(isOn: $child.isSomething)时，又会出现Cannot find '$child' in scope的错误。

需要解决的核心问题：如何让getChildren()返回正确类型，支持$child.isSomething这类绑定用法？

问题根源 #

• Child是ObservableObject，直接访问child.$isSomething得到的是发布者（Publisher），而非SwiftUI需要的Binding类型。
• $child的写法仅适用于被@StateObject/@ObservedObject修饰的对象，这里的child是数组中的元素，未被这些属性包装器修饰，因此无法直接用$前缀获取绑定。

解决方案 #

方案1：将Child改为值类型struct（推荐） #

如果Child不需要作为独立的ObservableObject，改成struct更符合SwiftUI数据流设计，可直接生成绑定：

// 修改Child为struct，去掉ObservableObject和@Published
struct Child : Codable, Hashable, Identifiable {
    let id = UUID() // 遵循Identifiable，简化ForEach使用
    static func == (lhs: Child, rhs: Child) -> Bool {
        return lhs.name == rhs.name && lhs.isSomething == rhs.isSomething
    }

    func hash(into hasher: inout Hasher) {
        hasher.combine(name)
        hasher.combine(isSomething)
    }

    let name: String
    var isSomething: Bool
}

// 修改Parent的方法，返回绑定数组
class Parent : Codable, ObservableObject {
    @Published public var children: [Child]?

    // 返回对应name的Child的Binding数组
    public func getChildrenBinding(with name: String) -> [Binding<Child>] {
        guard let children = children else { return [] }
        return children.indices
            .filter { children[$0].name == name }
            .map { $children[$0] }
    }
}

// 修改View中的ForEach使用绑定
struct MyView : View {
    @ObservedObject var parent: Parent
    var names: [String]

    var body: some View {
        ForEach(names, id: \.self) { name in
            ForEach(parent.getChildrenBinding(with: name), id: \.id) { $child in
                Toggle(isOn: $child.isSomething) {
                    Text(child.name)
                }
            }
        }
    }
}

方案2：保留Child为类，手动构建Binding #

如果必须保留Child的ObservableObject身份，可手动为isSomething创建Binding：

struct MyView : View {
    @ObservedObject var parent: Parent
    var names: [String]

    var body: some View {
        ForEach(names, id: \.self) { name in
            ForEach(parent.getChildren(with: name), id: \.self) { child in
                Toggle(isOn: Binding(
                    get: { child.isSomething },
                    set: { child.isSomething = $0 }
                )) {
                    Text(child.name)
                }
            }
        }
    }
}

关键说明 #

• SwiftUI的Binding需要关联到@State/@Published等修饰的数据源，值类型（struct）可通过数组索引直接生成绑定，引用类型（class）则需手动构建。
• 优先使用值类型作为数据模型，能减少状态管理复杂度，更适配SwiftUI的响应式设计。

内容的提问来源于stack exchange，提问作者meaning-matters