ian's questions

在下面的代码中我无法选择任何列表项：

import SwiftUI
import SwiftData

struct ItemView: View {
    
    @Environment(\.modelContext) private var context
    @Query(sort: \Item.title) private var items: [Item]
    
    @State private var selection: String? = nil
    
    var body: some View {
        if items.isEmpty {
            ContentUnavailableView("Enter your first item.", systemImage: "bookmark.fill")
        } else {
            List(items, id: \.self, selection: $selection) { item in
                Text(item.title)
            }
        }
    }
}

但是，在一个非常相似的示例中，该示例使用数组作为列表项而不是数据库，我可以选择项目：

import SwiftUI

struct ContentView: View {
    @State private var selection: String?
    @State private var isOn: Bool = false
    
    let names = [
        "Cyril",
        "Lana",
        "Mallory",
        "Sterling"
    ]

    var body: some View {
        NavigationStack {
            List(names, id: \.self, selection: $selection) { name in
                Toggle(isOn: $isOn) {
                    Text(name)
                }
            }
            .navigationTitle("List Selection")
            .toolbar {
                
            }
        }
    }
}

我的控制台日志显示：

Can't find or decode reasons
Failed to get or decode unavailable reasons
NSBundle file:///System/Library/PrivateFrameworks/MetalTools.framework/ principal class is nil because all fallbacks have failed

我做错什么了？

尝试在视图中初始化 SwiftData 查询时收到以下错误：

 Error: Cannot convert value of type 'PredicateExpressions.Equal<PredicateExpressions.KeyPath
<PredicateExpressions.Variable<Array<Todo>.Element>, Int>, PredicateExpressions.KeyPath<PredicateExpressions.Value<Section>, 
Int>>'(aka'PredicateExpressions.Equal<PredicateExpressions.
KeyPath<PredicateExpressions.Variable<Todo>, Int>, PredicateExpressions.KeyPath<PredicateExpressions.Value<Section>, 
Int>>') to closure result type 'any StandardPredicateExpression<Bool>'

TodoView.swift

import SwiftUI
import SwiftData

struct TodoView: View {
    
    @Query var todos: [Todo]
    
    @EnvironmentObject var currentSection: Section
    
    @Environment(\.modelContext) var modelContext
    
    var DWMY = ["D","W","M","Y"]
    
    var body: some View {
        List {
            ForEach(todos) { todo in
                HStack {
                    if todo.completed == false {
                        Text("[ ]")
                    } else {
                        Text("[X]")
                    }
                    Text(todo.name)
                    Text(DWMY[todo.section])
                }
            }
            .onDelete(perform: deleteToDo)
        }
        .navigationBarTitleDisplayMode(.inline)
    }
    
    init(todoSection: Section) {
        _todos = Query(filter: #Predicate { todo in
            todo.section == currentSection.section
        })
    }
    
    func deleteToDo(at offsets: IndexSet ) {
           for offset in offsets {
               let todo = todos[offset]
               modelContext.delete(todo)
           }
    }
}

当我尝试为查询提供值时会发生错误，currentSection.section如果我currentSection.section用硬编码的Int替换则不会出现任何错误。

据我所知，发生这种情况是因为我的环境ToDoView.swift直到Body创建后才被传递下去，因此发生currentSection.section时不存在init。

currentSection.section将我的价值传递到的正确方法是什么init？