A button with a progress indicator for SwiftUI

LoadingButton.swift

//
//  LoadingButton.swift
//  App
//
//  Created by Evan Coleman on 12/26/22.
//

import SwiftUI

struct LoadingButton<DefaultLabel: View, LoadingLabel: View>: View {

    var action: () async -> Void
    var label: DefaultLabel
    var loadingLabel: LoadingLabel

    @State private var isLoading: Bool = false

    var body: some View {
        Button(action: {
            Task {
                isLoading = true
                await action()
                isLoading = false
            }
        }) {
            if isLoading {
                loadingLabel
            } else {
                label
            }
        }
    }

    init(
        action: @escaping () async -> Void,
        label: () -> DefaultLabel,
        loadingLabel: () -> LoadingLabel
    ) {
        self.action = action
        self.label = label()
        self.loadingLabel = loadingLabel()
    }

    init(
        _ label: String,
        action: @escaping () async -> Void
    ) where DefaultLabel == Text, LoadingLabel == AnyView {
        self.action = action
        self.label = Text(label)
        self.loadingLabel = AnyView(
            ProgressView()
                .progressViewStyle(.circular)
        )
    }
}

struct LoadingButton_Previews: PreviewProvider {
    static var previews: some View {
        VStack(spacing: 40) {
            LoadingButton("Click Me") {
                try? await Task.sleep(for: .seconds(2))
            }

            LoadingButton(
                action: { try? await Task.sleep(for: .seconds(2)) }
            ) {
                Text("Click Me")
                    .frame(width: 140)
            } loadingLabel: {
                ProgressView()
                    .progressViewStyle(.circular)
                    .frame(width: 140)
            }
            .buttonStyle(.bordered)
        }
    }
}