Display a different RevenueCat paywall based on current size class in SwiftUI

OfferingDecider.swift

//
//  OfferingDecider.swift
//
//  Created by Cody Kerns on 11/25/24.
//

import Foundation
import SwiftUI
import RevenueCat
import RevenueCatUI

/// In the RevenueCat dashboard, add an Offering Metadata key for an alternative offering identifier to present if the size class isn't compact
/// e.g.
/// {
///    "alternative_offering_id": "my_other_offering_identifier"
/// }

struct OfferingDecider {
    static func getOffering(for sizeClass: UserInterfaceSizeClass?) async -> Offering? {
        do {
            let offerings: Offerings = try await Purchases.shared.offerings()

            // if there isn't an offering configured, return nil
            guard let currentOffering = offerings.current else { return nil }

            // if the size class is compact, return the standard offering
            guard sizeClass == .regular else { return offerings.current }

            if let alternativeOfferingId = currentOffering.metadata["alternative_offering_id"] as? String {
                // if there's an alt offering id set in metadata, return the offering with that id
                // if it's nil, return the current offering
                return offerings.all[alternativeOfferingId] ?? currentOffering
            } else {
                // no alternative id set, just return the current offering
                return currentOffering
            }
        } catch let err {
            print("Error fetching offerings: \(err)")
            return nil
        }
    }
}

class ExampleViewModel: ObservableObject {
    @State
    var shouldDisplayPaywall = false

    var paywallOffering: Offering? = nil

    func displayPaywall(for sizeClass: UserInterfaceSizeClass? = nil) {
        Task {
            if let offering = await OfferingDecider.getOffering(for: sizeClass) {
                paywallOffering = offering
                shouldDisplayPaywall = true
            }
        }
    }
}

struct ExampleView: View {
    @StateObject var viewModel: ExampleViewModel

    @Environment(\.horizontalSizeClass) private var horizontalSizeClass

    var body: some View {
        List {
            Button("Show Paywall") {
                viewModel.displayPaywall(for: horizontalSizeClass)
            }
        }
        .sheet(isPresented: $viewModel.shouldDisplayPaywall) {
            if let paywallOffering = viewModel.paywallOffering {
                PaywallView(offering: paywallOffering)
            } else {
                PaywallView()
            }
        }
    }
}