SwiftUI中无法访问绑定数组元素的问题求助

问题场景 #

定义Reminder结构体后，在主视图用@State声明其数组并传递给子视图ReminderListView，子视图通过@Binding接收数组。在子视图的ForEach中遍历绑定数组访问元素属性时出现错误。

Reminder结构体代码 #

struct Reminder: Identifiable, Hashable {
    var id = UUID() 
    var title: String
    var time: Date 
    var rangeStart: Date
    var rangeEnd: Date
    var frequency: Int
    var sound: String 
    var specificTimeSet: Bool
    var remindThroughoutHour: Bool
}

错误的ReminderListView代码 #

struct ReminderListView: View {
    @Binding var reminders: [Reminder]
    
    var body: some View {
        NavigationView {
            if reminders.isEmpty {
                VStack {
                    Text("You’ve no Reminders")
                        .font(.title2)
                        .foregroundColor(.gray)
                        .padding()
                    Spacer()
                }
                .navigationTitle("Your Reminders")
            } else {
                List  {
                    ForEach($reminders) { reminder in
                        HStack {
                            Text(reminder.title)
                            Spacer()
                            NavigationLink(destination: CreateReminderView(reminders: $reminders, reminderToEdit: reminder)) {
                                Text("Edit")
                                    .foregroundColor(.blue)
                            }
                            Button(action: {
                                deleteReminder(reminder.wrappedValue)
                            }) {
                                Image(systemName: "trash")
                                    .foregroundColor(.red)
                            }
                        }
                    }
                }
                .navigationTitle("Your Reminders")
            }
        }

    }
}

遇到的错误 #

1. 访问reminder.title时出现错误：Initializer 'init(_:)' requires that 'Binding<String>' conform to 'StringProtocol'
2. 尝试修改为ForEach($reminders) { $reminder in后出现新错误：

   No exact matches in call to initializer
   Candidate expects value of type 'Range<Int>' for parameter #1 (got 'Binding<[Reminder]>') (SwiftUICore.ForEach)
   Found candidate with type '(Binding<Array<Reminder>>, @escaping (SectionConfiguration) -> _) -> ForEach<ForEachSectionCollection<_>, SectionConfiguration.ID, _>'
   Inferred projection type 'Int' is not a property wrapper'
   

解决方案 #

核心问题原因 #

• 用ForEach($reminders)遍历绑定数组时，闭包参数reminder是Binding<Reminder>类型，直接访问reminder.title得到的是Binding<String>，而Text需要接收String类型，因此报错。
• 错误修改时的$reminder写法不符合SwiftUI绑定遍历语法，导致类型推断失败。

正确实现方式 #

有两种可行的修正方案：

方案1：通过wrappedValue访问原始值

在展示属性时，用reminder.title.wrappedValue获取原始String值，保持闭包参数为Binding<Reminder>类型：

struct ReminderListView: View {
    @Binding var reminders: [Reminder]
    
    var body: some View {
        NavigationView {
            if reminders.isEmpty {
                VStack {
                    Text("You’ve no Reminders")
                        .font(.title2)
                        .foregroundColor(.gray)
                        .padding()
                    Spacer()
                }
                .navigationTitle("Your Reminders")
            } else {
                List  {
                    ForEach($reminders) { reminder in
                        HStack {
                            Text(reminder.title.wrappedValue)
                            Spacer()
                            NavigationLink(destination: CreateReminderView(reminders: $reminders, reminderToEdit: reminder)) {
                                Text("Edit")
                                    .foregroundColor(.blue)
                            }
                            Button(action: {
                                deleteReminder(reminder.wrappedValue)
                            }) {
                                Image(systemName: "trash")
                                    .foregroundColor(.red)
                            }
                        }
                    }
                }
                .navigationTitle("Your Reminders")
            }
        }
    }
    
    private func deleteReminder(_ reminder: Reminder) {
        if let index = reminders.firstIndex(where: { $0.id == reminder.id }) {
            reminders.remove(at: index)
        }
    }
}

方案2：使用绑定投影语法糖（推荐）

在ForEach闭包中用$reminder语法，此时reminder自动解析为Reminder类型，需要绑定属性时直接用$reminder.title：

struct ReminderListView: View {
    @Binding var reminders: [Reminder]
    
    var body: some View {
        NavigationView {
            if reminders.isEmpty {
                VStack {
                    Text("You’ve no Reminders")
                        .font(.title2)
                        .foregroundColor(.gray)
                        .padding()
                    Spacer()
                }
                .navigationTitle("Your Reminders")
            } else {
                List  {
                    ForEach($reminders) { $reminder in
                        HStack {
                            Text(reminder.title)
                            Spacer()
                            NavigationLink(destination: CreateReminderView(reminders: $reminders, reminderToEdit: $reminder)) {
                                Text("Edit")
                                    .foregroundColor(.blue)
                            }
                            Button(action: {
                                deleteReminder(reminder)
                            }) {
                                Image(systemName: "trash")
                                    .foregroundColor(.red)
                            }
                        }
                    }
                }
                .navigationTitle("Your Reminders")
            }
        }
    }
    
    private func deleteReminder(_ reminder: Reminder) {
        if let index = reminders.firstIndex(where: { $0.id == reminder.id }) {
            reminders.remove(at: index)
        }
    }
}

注意事项 #

• 使用方案2时，CreateReminderView的reminderToEdit参数需定义为Binding<Reminder>类型，才能接收$reminder。
• 确保Reminder实现Identifiable协议（已实现），保证ForEach能正确识别数组元素。

内容的提问来源于stack exchange，提问作者user15561906