编辑代码

var myString = "Hello world!     -  swift.jsrun.net"
print(myString)
//
// CombineAPI.swift
// SwiftOnly (iOS)
//
// Created by Ming Dai on 2021/11/4.
//

import SwiftUI
import Combine

struct CombineAPI: View {
  var body: some View {
    RepListView(vm: .init())
  }
}

struct RepListView: View {
  @ObservedObject var vm: RepListVM

  var body: some View {
    NavigationView {
      List(vm.repos) { rep in
        RepListCell(rep: rep)
      }
      .alert(isPresented: $vm.isErrorShow) { () -> Alert in
        Alert(title: Text("出错了"), message: Text(vm.errorMessage))
      }
      .navigationBarTitle(Text("仓库"))
    }
    .onAppear {
      vm.apply(.onAppear)
    }
  }
}

struct RepListCell: View {
  @State var rep: RepoModel
  var body: some View {
    HStack() {
      VStack() {
        AsyncImage(url: URL(string: rep.owner.avatarUrl ?? ""), content: { image in
          image
            .resizable()
            .aspectRatio(contentMode: .fit)
            .frame(width: 100, height: 100)
        },
        placeholder: {
          ProgressView()
            .frame(width: 100, height: 100)
        })
        Text("\(rep.owner.login)")
          .font(.system(size: 10))
      }
      VStack(alignment: .leading, spacing: 10) {
        Text("\(rep.name)")
          .font(.title)
        Text("\(rep.stargazersCount)")
          .font(.title3)
        Text("\(String(describing: rep.description ?? ""))")
        Text("\(String(describing: rep.language ?? ""))")
          .font(.title3)
      }
      .font(.system(size: 14))
    }

  }
}
Amor.Y:
//
// CombineAPI.swift
// SwiftOnly (iOS)
//
// Created by Ming Dai on 2021/11/4.
//

import SwiftUI
import Combine

struct CombineAPI: View {
  var body: some View {
    RepListView(vm: .init())
  }
}

struct RepListView: View {
  @ObservedObject var vm: RepListVM

  var body: some View {
    NavigationView {
      List(vm.repos) { rep in
        RepListCell(rep: rep)
      }
      .alert(isPresented: $vm.isErrorShow) { () -> Alert in
        Alert(title: Text("出错了"), message: Text(vm.errorMessage))
      }
      .navigationBarTitle(Text("仓库"))
    }
    .onAppear {
      vm.apply(.onAppear)
    }
  }
}

struct RepListCell: View {
  @State var rep: RepoModel
  var body: some View {
    HStack() {
      VStack() {
        AsyncImage(url: URL(string: rep.owner.avatarUrl ?? ""), content: { image in
          image
            .resizable()
            .aspectRatio(contentMode: .fit)
            .frame(width: 100, height: 100)
        },
        placeholder: {
          ProgressView()
            .frame(width: 100, height: 100)
        })
        Text("\(rep.owner.login)")
          .font(.system(size: 10))
      }
      VStack(alignment: .leading, spacing: 10) {
        Text("\(rep.name)")
          .font(.title)
        Text("\(rep.stargazersCount)")
          .font(.title3)
        Text("\(String(describing: rep.description ?? ""))")
        Text("\(String(describing: rep.language ?? ""))")
          .font(.title3)
      }
      .font(.system(size: 14))
    }

  }
}


// MARK: Repo View Model
final class RepListVM: ObservableObject, UnidirectionalDataFlowType {
  typealias InputType = Input
  private var cancellables: [AnyCancellable] = []

  // Input
  enum Input {
    case onAppear
  }
  func apply(_ input: Input) {
    switch input {
    case .onAppear:
      onAppearSubject.send(())
    }
  }
  private let onAppearSubject = PassthroughSubject<Void, Never>()

  // Output
  @Published private(set) var repos: [RepoModel] = []
  @Published var isErrorShow = false
  @Published var errorMessage = ""
  @Published private(set) var shouldShowIcon = false

  private let resSubject = PassthroughSubject<SearchRepoModel, Never>()
  private let errSubject = PassthroughSubject<APISevError, Never>()

  private let apiSev: APISev

  init(apiSev: APISev = APISev()) {
    self.apiSev = apiSev
    bindInputs()
    bindOutputs()
  }

  private func bindInputs() {
    let req = SearchRepoRequest()
    let resPublisher = onAppearSubject
      .flatMap { [apiSev] in
        apiSev.response(from: req)
          .catch { [weak self] error -> Empty<SearchRepoModel, Never> in
            self?.errSubject.send(error)
            return .init()
          }
      }
    let resStream = resPublisher
      .share()
      .subscribe(resSubject)

    // 其它异步事件,比如日志等操作都可以做成Stream加到下面数组内。
    cancellables += [resStream]
  }

  private func bindOutputs() {
    let repStream = resSubject
      .map {
        $0.items
      }
      .assign(to: \.repos, on: self)
    let errMsgStream = errSubject
      .map { error -> String in
        switch error {
        case .resError: return "network error"
        case .parseError: return "parse error"
        }
      }
      .assign(to: \.errorMessage, on: self)
    let errStream = errSubject
      .map { _ in
        true
      }
      .assign(to: \.isErrorShow, on: self)
    cancellables += [repStream,errStream,errMsgStream]
  }

}

Amor.Y:
protocol UnidirectionalDataFlowType {
  associatedtype InputType
  func apply(_ input: InputType)
}

// MARK: Repo Request and Models

struct SearchRepoRequest: APIReqType {
  typealias Res = SearchRepoModel

  var path: String {
    return "/search/repositories"
  }
  var qItems: [URLQueryItem]? {
    return [      .init(name: "q", value: "Combine"),
      .init(name: "order", value: "desc")
    ]
  }
}

struct SearchRepoModel: Decodable {
  var items: [RepoModel]
}

struct RepoModel: Decodable, Hashable, Identifiable {
  var id: Int64
  var name: String
  var fullName: String
  var description: String?
  var stargazersCount: Int = 0
  var language: String?
  var owner: OwnerModel
}

struct OwnerModel: Decodable, Hashable, Identifiable {
  var id: Int64
  var login: String
  var avatarUrl: String?
}


// MARK: API Request Fundation

protocol APIReqType {
  associatedtype Res: Decodable
  var path: String { get }
  var qItems: [URLQueryItem]? { get }
}

protocol APISevType {
  func response<Request>(from req: Request) -> AnyPublisher<Request.Res, APISevError> where Request: APIReqType
}

final class APISev: APISevType {
  private let rootUrl: URL
  init(rootUrl: URL = URL(string: "https://api.github.com")!) {
    self.rootUrl = rootUrl
  }

  func response<Request>(from req: Request) -> AnyPublisher<Request.Res, APISevError> where Request : APIReqType {
    let path = URL(string: req.path, relativeTo: rootUrl)!
    var comp = URLComponents(url: path, resolvingAgainstBaseURL: true)!
    comp.queryItems = req.qItems
    print(comp.url?.description ?? "url wrong")
    var req = URLRequest(url: comp.url!)
    req.addValue("application/json", forHTTPHeaderField: "Content-Type")

    let de = JSONDecoder()
    de.keyDecodingStrategy = .convertFromSnakeCase
    return URLSession.shared.dataTaskPublisher(for: req)
      .map { data, res in
        print(String(decoding: data, as: UTF8.self))
        return data
      }
      .mapError { _ in
        APISevError.resError
      }
      .decode(type: Request.Res.self, decoder: de)
      .mapError(APISevError.parseError)
      .receive(on: RunLoop.main)
      .eraseToAnyPublisher()
  }
}

enum APISevError: Error {
  case resError
  case parseError(Error)
}