Blog post: SwiftUI with UICollectionView - 15. Use @EnvironementObject instead of @State when embedding SwiftUI Views inside of UICollectionViewCell

swiftui-card-view-with-environmentobject.swift

// MARK: Card

protocol CardContent {
    var id: String { get }
    var imageName: String { get }
    var title: String { get }
    var description: String { get }
}

struct Card: View {

    typealias Content = CardContent

    let content: Content

    @EnvironmentObject var heartsProvider: HeartsProvider

    var body: some View {
        ZStack(alignment: .topTrailing) {
            VStack(alignment: .leading, spacing: 8) {
                Image(content.imageName)
                    .fitToAspectRatio(3/2)
                    .clipShape(RoundedRectangle(cornerRadius: 4))

                Text(content.title)
                    .font(.headline)

                Text(content.description)
                    .font(.body)
                    .lineLimit(1)

                Spacer()
            }

            HeartButton(isHearted: heartsProvider.isHearted(id: content.id), action: {
                self.heartsProvider.toggle(id: content.id)
            }).padding()
        }
    }
}

// MARK: HeartsProvider

import SwiftUI

class HeartsProvider: ObservableObject {
    
    @Published var hearts: [String] = []
    
    func isHearted(id: String) -> Bool {
        return hearts.contains(id)
    }
    
    func toggle(id: String) {
        // ...
    }
}

// MARK: App

@main
struct PlaygroundApp: App {    
    var body: some Scene {
        WindowGroup {
            ContentView()
                .environmentObject(HeartsProvider())
        }
    }
}