Blog: ObservableObjects and Protocols - Protocol in SwiftUI

blog--observableobject+protocols--protocol-in-swiftui.swift

// Copyright 2021 Expedia, Inc.
// SPDX-License-Identifier: Apache-2.0

import SwiftUI

struct PriceView: View {
    
    @State private var price: Price?
    
    let pricing: PriceRequesting
    
    var body: some View {
        Group {
            if let price = price {
                Text(price.amount).bold() + Text(" \(price.description)").font(.system(size: 12))
            } else {
                Text("Price not available")
                    .italic()
                    .foregroundColor(.gray)
            }
        }
        .font(.system(size: 16))
        .onReceive(pricing.pricePublisher, perform: { price in
            self.price = price
        })
    }
}

struct Demo: View {
    
    @StateObject private var pricing = PricingProvider()
    
    var body: some View {
        VStack(alignment: .center, spacing: 8) {
            PriceView(pricing: pricing)
            
            Button("Fetch price", action: {
                pricing.fetch()
            })
            .buttonStyle(PrimaryButtonStyle())
        }
    }
}