Apple rilascia iOS 13 Beta 8 agli sviluppatori

// RoomStore.swift
import Foundation

class RoomStore: ObservableObject {
    @Published var rooms: [Room] = []
}

struct Room: Identifiable {
    var id: UUID
    var name: String
    var capacity: Int
    var hasVideo: Bool
}

// ContentView.swift
import SwiftUI

struct ContentView: View {
    @ObservedObject var store: RoomStore

    var body: some View {
        NavigationView {
            List(store.rooms) { room in
                RoomCell(room: room)
            }
            .navigationBarTitle("Rooms")
        }
    }
}

NavigationView {
    MyMasterView()
    MyDetailView()
}
.navigationViewStyle(DoubleColumnNavigationViewStyle())

List(0..<5) {
    Text("Rooms")
}

struct LandmarkList: View {
    var landmark: [Landmark]
    @Binding var favorites: Set<Landmark>

    var body: some View {
        List(landmarks) { landmark in
            Toggle(landmark.name, isOn: self.$favorites.contains(landmarkID))
        }
    }
}

extension Set {
    subscript(member: Element) -> Bool {
        get { contains(member) }
        set {
            if newValue {
                insert(member)
            } else {
                remove(member)
            }
        }
    }
}

struct LandmarkList: View {
    @Binding var landmark: [Landmark]

    var body: some View {
        List(landmarks) { landmark in
            Toggle(landmark.value.name, isOn: landmark[\.isFavorite])
        }
    }
}

struct IndexedCollection<Base: RandomAccessCollection>: RandomAccessCollection {
    typealias Index = Base.Index
    typealias Element = (index: Index, element: Base.Element)

    let base: Base

    var startIndex: Index { base.startIndex }

    var endIndex: Index { base.startIndex }

    func index(after i: Index) -> Index {
        base.index(after: i)
    }

    func index(before i: Index) -> Index {
        base.index(before: i)
    }

    func index(_ i: Index, offsetBy distance: Int) -> Index {
        base.index(i, offsetBy: distance)
    }

    subscript(position: Index) -> Element {
        (index: position, element: base[position])
    }
}

extension RandomAccessCollection {
    func indexed() -> IndexedCollection<Self> {
        IndexedCollection(base: self)
    }
}

struct LandmarkList: View {
    @Binding var landmarks: [Landmark]

    var body: some View {
        List(landmarks.indexed(), id: \.1.id) { (index, landmark) in
            Toggle(landmark.name, isOn: self.$landmarks[index].isFavorite)
        }
    }
}