ContentPrepareView.swift

struct ContentPrepareView<Content, Failure, Loading>: View where Content: View, Failure: View, Loading: View {
  @State private var viewContent: ViewContent = .loading

  @ViewBuilder let content: () -> Content
  @ViewBuilder let failure: (Error, @escaping () async -> Void) -> Failure
  @ViewBuilder let loading: () -> Loading
  let task: () async throws -> Void

  init(content: @escaping () -> Content,
       failure: @escaping (Error, @escaping () async -> Void) -> Failure = { FailureView(error: $0, retryTask: $1) },
       loading: @escaping () -> Loading = { ProgressView() },
       task: @escaping () async throws -> Void) {
    self.content = content
    self.failure = failure
    self.loading = loading
    self.task = task
  }

  var body: some View {
    Group {
      switch viewContent {
      case .content:
        content()
      case .failure(let error):
        failure(error, loadTask)
      case .loading:
        loading()
      }
    }
    .onLoad(perform: loadTask)
  }
  // redacted
}