Allows us to filter `Binding`s while keeping everything bindable — so long as they wrap collections of `Identifiable` elements.

Binding+Filter.swift

import SwiftUI

extension Binding where Value: MutableCollection, Value: RangeReplaceableCollection, Value.Element: Identifiable {
  func filter(_ isIncluded: @escaping (Value.Element)->Bool) -> Binding<[Value.Element]> {
    return Binding<[Value.Element]>(
      get: { 
        // The binding returns a filtered subset of the original wrapped collection.
        self.wrappedValue.filter(isIncluded) 
      },
      set: { newValue in
        // Assignments to the binding's wrapped value are compared with IDs in the original biding's collection. 
        // If they match, they are replaced.
        // If no match is found, they are appended.
        newValue.forEach { newItem in
          guard let i = self.wrappedValue.firstIndex(where: { $0.id == newItem.id }) else {
            self.wrappedValue.append(newItem)
            return
          }
          self.wrappedValue[i] = newItem 
        }
      }
    )
  }
}

Example.swift

// MARK: - CONTENT VIEW
struct ContentView: View {
  @ObservedObject var model: AppModel = AppModel()
  
  var body: some View {
    NavigationView {
      List {
        NavigationLink(destination: TodosView(todos: $model.todos)) {
          Text("All Todos")
        }
        // This important part is right here ⤵️
        NavigationLink(destination: TodosView(todos: $model.todos.filter { $0.isCritical })) {
          Text("Critical Todos")
        }
      }
    }
  }
}


// MARK: - OTHER SUBVIEWS 
struct TodosView: View {
  @Binding var todos: [Todo]
  
  var body: some View {
    List {
      ForEach(todos.indices) { i in
        TodoView(todo: self.todos[i])
          .onTapGesture {
            // Note we can still propegate updates, even though it’s (potentially) a subset.
            self.todos[i].isComplete.toggle()
        }
      }
    }
  }
}


struct TodoView: View {
  let todo: Todo
  
  var body: some View {
    HStack {
      Image(systemName: todo.isComplete ? "checkmark.square.fill" : "square")
      Text(todo.title)
    }
  }
}


// MARK: - MODELS AND STUFF
struct Todo: Identifiable {
  let id = UUID()
  let title: String
  let isCritical: Bool
  var isComplete: Bool = false
  
  init(title: String, isCritical: Bool = false) {
    self.title = title
    self.isCritical = isCritical
  }
}


class AppModel: ObservableObject {
  @Published var todos: [Todo] = [
    Todo(title: "Write blog post"),
    Todo(title: "Write another blog post"),
    Todo(title: "Seriously, there are like 30 blog posts I have to write"),
    Todo(title: "post a quick gist", isCritical: true),
  ]
}