Using queries combined with arrays in RealmSwift

ContentView.swift

import SwiftUI
import RealmSwift

struct ContentView: View {
  @ObservedObject var search = TodoSearchData()
  
  var body: some View {
    VStack {
      List {
        HStack {
          ZStack {
            RoundedRectangle(cornerRadius: 10)
              .fill(Color(red: 239 / 255,
                          green: 239 / 255,
                          blue: 241 / 255))
              .frame(height: 36)
            
            HStack(spacing: 6) {
              Spacer()
                .frame(width: 0)
              Image(systemName: "magnifyingglass")
                .foregroundColor(.gray)
              TextField("テキスト", text: $search.text).onSubmit {
                search.run()
              }
              .submitLabel(.search)
            }
          }
          .padding(.horizontal)
        }
        
        HStack {
          Button("日付", action: {
            search.isDate.toggle()
            search.run()
          })
          .buttonStyle(.bordered)
          .controlSize(.small)
        }
        .frame(maxWidth: .infinity, alignment: .leading)
        if search.isDate {
          VStack(alignment: .leading){
            Text("日付").font(.caption)
            HStack {
              DatePicker("", selection: $search.dateFrom, displayedComponents: .date)
                .onChange(of: search.dateFrom, perform: { _ in
                  search.run()
                })
                .datePickerStyle(.compact)
              Text("〜")
              DatePicker("", selection: $search.dateTo, displayedComponents: .date)
                .onChange(of: search.dateTo, perform: { _ in
                  search.run()
                })
                .datePickerStyle(.compact)
            }
          }
          .frame(maxWidth: .infinity, alignment: .leading)
          .labelsHidden()
          .environment(\.locale, .init(identifier: "ja_JP"))
          .font(.body)
          .ignoresSafeArea()
        }
        
        if let todos = search.results {
          ForEach(todos.indices, id: \.self) { idx in
            Text(todos[idx].title + " " + todos[idx].date.string)
          }
        }
      }
    }
    .onAppear {
      UITextField.appearance().clearButtonMode = .whileEditing
      search.run()
    }
  }
}

class TodoSearchData: ObservableObject {
  @Published var isDate = false
  @Published var dateFrom = Date()
  @Published var dateTo = Date()
  @Published var text = ""
  @ObservedResults(Todo.self) var todos
  @Published var results: Results<Todo>?
  
  private func query(_ query: Query<Todo>) -> Query<Bool>? {
    var queries = [Query<Bool>]()
    if isDate {
      let dateFrom = dateFrom.from
      let dateTo = dateTo.to
      if dateFrom < dateTo {
        queries.append(query.date.contains(dateFrom...dateTo))
      }
    }
    
    if text != "" {
      queries.append(query.title.contains(text))
    }
    
    return queries.andCompound()
  }
  
  func run(){
    results = todos.where{ todo in
      query(todo) ?? (todo.title != "")
    }
    .sorted(byKeyPath: "_id", ascending: true)
  }
}

func DateToString(date: Date) -> String {
  let f = DateFormatter()
  f.dateFormat = "yyyy/MM/dd"
  f.locale = Locale(identifier: "ja_JP")
  return f.string(from: date)
}

extension Date {
  var string: String {
    return DateToString(date: self)
  }
  var from: Date {
    return Calendar.current.date(bySettingHour: 0, minute: 0, second: 0, of: self)!
  }
  var to: Date {
    return Calendar.current.date(bySettingHour: 23, minute: 59, second: 59, of: self)!
  }
}

// References
// Compound Array of Query<Bool> #7731
// https://github.com/realm/realm-swift/issues/7731
extension Sequence where Element == Query<Bool> {
  func andCompound() -> Query<Bool>? {
    var iterator = makeIterator()
    var accumulator = iterator.next()
    while let element = iterator.next() {
      if let unwrappedAccumulator = accumulator {
        accumulator = unwrappedAccumulator && element
      } else {
        accumulator = element
      }
    }
    return accumulator
  }
  
  func orCompound() -> Query<Bool>? {
    var iterator = makeIterator()
    var accumulator = iterator.next()
    while let element = iterator.next() {
      if let unwrappedAccumulator = accumulator {
        accumulator = unwrappedAccumulator || element
      } else {
        accumulator = element
      }
    }
    return accumulator
  }
}

TodoExampleApp.swift

import SwiftUI
import RealmSwift

let schemaVersion:UInt64 = 1

@main
struct TodoExampleApp: SwiftUI.App {
  var realm: Realm
  
  init(){
    let config = Realm.Configuration(schemaVersion: schemaVersion)
    Realm.Configuration.defaultConfiguration = config
   
    realm = try! Realm()
                 
//    let todo1 = Todo(value: ["title": "Hello1", "date": makeDate(2023, 10, 10)] as [String : Any])
//    let todo2 = Todo(value: ["title": "Hello2", "date": makeDate(2023, 11, 20)] as [String : Any])
//    let todo3 = Todo(value: ["title": "Hello3", "date": makeDate(2023, 12, 30)] as [String : Any])

    try! realm.write {
      let _ = realm.objects(Todo.self)
//      realm.add([todo1, todo2, todo3])
    }
  }
  
  var body: some Scene {
    WindowGroup {
      ContentView()
        .environment(\.realm, realm)
    }
  }
}

func makeDate(_ year: Int,_ month: Int,_ day: Int) -> Date {
  let date = Calendar.current.date(from: DateComponents(year : year, month: month, day: day)) ?? Date()
  return Calendar.current.startOfDay(for: date)
}

final class Todo: Object, ObjectKeyIdentifiable {
  @Persisted(primaryKey: true) var _id: ObjectId
  @Persisted var title = ""
  @Persisted var date = Date()
}