SwiftUI框架详细解析（十七） —— 基于SwiftUI简

2021-01-02 本文已影响0人刀客传奇

版本记录

版本号	时间
V1.0	2021.01.02 星期六

前言

今天翻阅苹果的API文档，发现多了一个框架SwiftUI，这里我们就一起来看一下这个框架。感兴趣的看下面几篇文章。
1. SwiftUI框架详细解析（一） —— 基本概览（一）
2. SwiftUI框架详细解析（二） —— 基于SwiftUI的闪屏页的创建（一）
3. SwiftUI框架详细解析（三） —— 基于SwiftUI的闪屏页的创建（二）
4. SwiftUI框架详细解析（四） —— 使用SwiftUI进行苹果登录（一）
5. SwiftUI框架详细解析（五） —— 使用SwiftUI进行苹果登录（二）
6. SwiftUI框架详细解析（六） —— 基于SwiftUI的导航的实现（一）
7. SwiftUI框架详细解析（七） —— 基于SwiftUI的导航的实现（二）
8. SwiftUI框架详细解析（八） —— 基于SwiftUI的动画的实现（一）
9. SwiftUI框架详细解析（九） —— 基于SwiftUI的动画的实现（二）
10. SwiftUI框架详细解析（十） —— 基于SwiftUI构建各种自定义图表（一）
11. SwiftUI框架详细解析（十一） —— 基于SwiftUI构建各种自定义图表（二）
12. SwiftUI框架详细解析（十二） —— 基于SwiftUI创建Mind-Map UI（一）
13. SwiftUI框架详细解析（十三） —— 基于SwiftUI创建Mind-Map UI（二）
14. SwiftUI框架详细解析（十四） —— 基于Firebase Cloud Firestore的SwiftUI iOS程序的持久性添加（一）
15. SwiftUI框架详细解析（十五） —— 基于Firebase Cloud Firestore的SwiftUI iOS程序的持久性添加（二）
16. SwiftUI框架详细解析（十六） —— 基于SwiftUI简单App的Dependency Injection应用（一）

源码

1. Swift

首先看下工程组织结构

下面就是源码了

1. PreferencesStore.swift

import Combine
import Foundation

protocol PreferencesStoreProtocol: ObservableObject {
  var friendsListPreference: PrivacyLevel { get set }
  var photosPreference: PrivacyLevel { get set }
  var feedPreference: PrivacyLevel { get set }
  var videoCallsPreference: PrivacyLevel { get set }
  var messagePreference: PrivacyLevel { get set }
  func resetPreferences()
}

final class PreferencesStore: PreferencesStoreProtocol {
  @Published var friendsListPreference = value(for: .friends, defaultValue: .friend) {
    didSet {
      set(value: photosPreference, for: .friends)
    }
  }

  @Published var photosPreference = value(for: .photos, defaultValue: .friend) {
    didSet {
      set(value: photosPreference, for: .photos)
    }
  }

  @Published var feedPreference = value(for: .feed, defaultValue: .friend) {
    didSet {
      set(value: feedPreference, for: .feed)
    }
  }

  @Published var videoCallsPreference = value(for: .videoCall, defaultValue: .closeFriend) {
    didSet {
      set(value: videoCallsPreference, for: .videoCall)
    }
  }

  @Published var messagePreference: PrivacyLevel = value(for: .message, defaultValue: .friend) {
    didSet {
      set(value: messagePreference, for: .message)
    }
  }

  func resetPreferences() {
    let defaults = UserDefaults.standard
    PrivacySetting.allCases.forEach { setting in
      defaults.removeObject(forKey: setting.rawValue)
    }
  }

  private static func value(for key: PrivacySetting, defaultValue: PrivacyLevel) -> PrivacyLevel {
    let value = UserDefaults.standard.string(forKey: key.rawValue) ?? ""
    return PrivacyLevel.from(string: value) ?? defaultValue
  }

  private func set(value: PrivacyLevel, for key: PrivacySetting) {
    UserDefaults.standard.setValue(value.title, forKey: key.rawValue)
  }
}

2. PrivacyLevel.swift

import Foundation

enum PrivacyLevel: Comparable {
  case everyone, friend, closeFriend

  var title: String {
    switch self {
    case .everyone:
      return "Everyone"
    case .friend:
      return "Friends only"
    case .closeFriend:
      return "Close friends only"
    }
  }

  static func from(string: String) -> PrivacyLevel? {
    switch string {
    case everyone.title:
      return everyone
    case friend.title:
      return friend
    case closeFriend.title:
      return closeFriend
    default:
      return nil
    }
  }
}

3. UserPreferencesView.swift

import SwiftUI
import Combine

struct UserPreferencesView<Store>: View where Store: PreferencesStoreProtocol {
  private var store: Store

  // swiftlint:disable:next force_unwrapping
  init(store: Store = DIContainer.shared.resolve(type: Store.self)!) {
    self.store = store
  }

  var body: some View {
    NavigationView {
      VStack {
        PreferenceView(title: .photos, value: store.photosPreference) { value in
          store.photosPreference = value
        }
        PreferenceView(title: .friends, value: store.friendsListPreference) { value in
          store.friendsListPreference = value
        }
        PreferenceView(title: .feed, value: store.feedPreference) { value in
          store.feedPreference = value
        }
        PreferenceView(title: .videoCall, value: store.videoCallsPreference) { value in
          store.videoCallsPreference = value
        }
        PreferenceView(title: .message, value: store.messagePreference) { value in
          store.messagePreference = value
        }
        Spacer()
      }
    }.navigationBarTitle("Privacy preferences")
  }
}

struct PreferenceView: View {
  private let title: PrivacySetting
  private let value: PrivacyLevel
  private let onPreferenceUpdated: (PrivacyLevel) -> Void

  init(title: PrivacySetting, value: PrivacyLevel, onPreferenceUpdated: @escaping (PrivacyLevel) -> Void) {
    self.title = title
    self.value = value
    self.onPreferenceUpdated = onPreferenceUpdated
  }

  var body: some View {
    HStack {
      Text(title.rawValue).font(.body)
      Spacer()
      PreferenceMenu(title: value.title, onPreferenceUpdated: onPreferenceUpdated)
    }.padding()
  }
}

struct PreferenceMenu: View {
  @State var title: String
  private let onPreferenceUpdated: (PrivacyLevel) -> Void

  init(title: String, onPreferenceUpdated: @escaping (PrivacyLevel) -> Void) {
    _title = State<String>(initialValue: title)
    self.onPreferenceUpdated = onPreferenceUpdated
  }

  var body: some View {
    Menu(title) {
      Button(PrivacyLevel.closeFriend.title) {
        onPreferenceUpdated(PrivacyLevel.closeFriend)
        title = PrivacyLevel.closeFriend.title
      }
      Button(PrivacyLevel.friend.title) {
        onPreferenceUpdated(PrivacyLevel.friend)
        title = PrivacyLevel.friend.title
      }
      Button(PrivacyLevel.everyone.title) {
        onPreferenceUpdated(PrivacyLevel.everyone)
        title = PrivacyLevel.everyone.title
      }
    }
  }
}

struct UserPreferencesView_Previews: PreviewProvider {
  static var previews: some View {
    UserPreferencesView(store: PreferencesStore())
  }
}

4. ProfileView.swift

import SwiftUI

struct ProfileView<ContentProvider>: View where ContentProvider: ProfileContentProviderProtocol {
  private let user: User
  @ObservedObject private var provider: ContentProvider

  init(
    // swiftlint:disable force_unwrapping
    provider: ContentProvider = DIContainer.shared.resolve(type: ContentProvider.self)!,
    user: User = DIContainer.shared.resolve(type: User.self)!
    // swiftlint:enable force_unwrapping
  ) {
    self.provider = provider
    self.user = user
  }

  var body: some View {
    NavigationView {
      ScrollView(.vertical, showsIndicators: true) {
        VStack {
          ProfileHeaderView(
            user: user,
            canSendMessage: provider.canSendMessage,
            canStartVideoChat: provider.canStartVideoChat
          )
          provider.friendsView
          provider.photosView
          provider.feedView
        }
      }
      .navigationTitle("Profile")
      .navigationBarItems(trailing: Button(action: {}) {
        NavigationLink(destination: UserPreferencesView<PreferencesStore>()) {
          Image(systemName: "gear")
        }
      })
    }
  }
}

struct ProfileView_Previews: PreviewProvider {
  static var previews: some View {
    typealias Provider = ProfileContentProvider<PreferencesStore>
    let container = DIContainer.shared
    container.register(type: PrivacyLevel.self, component: PrivacyLevel.friend)
    container.register(type: User.self, component: Mock.user())
    container.register(type: PreferencesStore.self, component: PreferencesStore())
    container.register(type: Provider.self, component: Provider())
    return ProfileView<Provider>()
  }
}

// MARK: - Profile views

struct PhotosView: View {
  private let photos: [String]

  init(photos: [String]) {
    self.photos = photos
  }

  var body: some View {
    VStack {
      Text("Recent photos").font(.title2)
      ScrollView(.horizontal, showsIndicators: false) {
        HStack {
          ForEach(photos, id: \.self) { url in
            ImageView(withURL: url).frame(width: 200, height: 200).clipped()
          }
        }
      }
    }
  }
}

struct UsersView: View {
  private let users: [User]
  private let title: String

  init(title: String, users: [User]) {
    self.users = users
    self.title = title
  }

  var body: some View {
    VStack {
      Text(title).font(.title2)
      ScrollView(.horizontal, showsIndicators: false) {
        HStack {
          ForEach(users, id: \.self) { user in
            VStack {
              ImageView(withURL: user.imageURL).frame(width: 80, height: 80).clipped()
              Text(user.name)
            }
          }
        }
      }
    }
  }
}

struct ProfileHeaderView: View {
  private let user: User
  private let canSendMessage: Bool
  private let canStartVideoChat: Bool

  init(user: User, canSendMessage: Bool, canStartVideoChat: Bool) {
    self.user = user
    self.canSendMessage = canSendMessage
    self.canStartVideoChat = canStartVideoChat
  }

  var body: some View {
    VStack {
      HStack(alignment: .center, spacing: 16) {
        Spacer()
        if canStartVideoChat {
          Button(action: {}) {
            Image(systemName: "video")
          }
        }
        if canSendMessage {
          Button(action: {}) {
            Image(systemName: "message")
          }
        }
      }.padding(.trailing)
      ImageView(withURL: user.imageURL).clipShape(Circle()).frame(width: 100, height: 100).clipped()
      Text(user.name).font(.largeTitle)
      HStack {
        Image(systemName: "location")
        Text(user.area).font(.subheadline)
      }.padding(2)
      Text(user.bio).font(.body).padding()
    }
  }
}

// MARK: - History feed views

struct HistoryFeedView: View {
  private let posts: [Post]

  init(posts: [Post]) {
    self.posts = posts
  }

  var body: some View {
    ScrollView(.vertical, showsIndicators: true) {
      VStack {
        Text("Recent posts").font(.title2)
        ForEach(posts, id: \.self) { post in
          PostView(post: post)
        }
      }
    }
  }
}

struct PostView: View {
  private let post: Post

  init(post: Post) {
    self.post = post
  }

  var body: some View {
    VStack {
      ImageView(withURL: post.pictureURL).frame(height: 200).clipped()
      HStack {
        Text(post.message)
        Spacer()
        HStack {
          Image(systemName: "hand.thumbsup")
          Text(String(post.likesCount))
        }
        HStack {
          Image(systemName: "bubble.right")
          Text(String(post.commentsCount))
        }
      }.padding()
    }
  }
}

struct RestrictedAccessView: View {
  var body: some View {
    VStack {
      Image(systemName: "eye.slash").padding()
      Text("The access to the full profile info is restricted")
    }
  }
}

5. ImageView.swift

import SwiftUI

struct ImageView: View {
  @ObservedObject var imageLoader: ImageLoader
  @State var image = UIImage(named: "img_placeholder", in: Bundle(for: ImageLoader.self), with: nil) ?? UIImage()

  init(withURL url: String) {
    self.imageLoader = ImageLoader(urlString: url)
  }

  var body: some View {
    Image(uiImage: image)
      .resizable()
      .aspectRatio(contentMode: .fill)
      .onReceive(imageLoader.didChange) { image in
        self.image = image
      }
  }
}

struct ImageView_Previews: PreviewProvider {
  static var previews: some View {
    Image(uiImage: UIImage(named: "img_placeholder") ?? UIImage())
      .resizable()
      .aspectRatio(contentMode: .fill)
      .frame(width: 100, height: 100)
      .clipped()
  }
}

6. SceneDelegate.swift

import UIKit
import SwiftUI

class SceneDelegate: UIResponder, UIWindowSceneDelegate {
  var window: UIWindow?

  typealias Provider = ProfileContentProvider<PreferencesStore>

  func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
    let container = DIContainer.shared
    container.register(type: PrivacyLevel.self, component: PrivacyLevel.friend)
    container.register(type: User.self, component: Mock.user())
    container.register(type: PreferencesStore.self, component: PreferencesStore())
    container.register(type: Provider.self, component: Provider())
    let profileView = ProfileView<Provider>()
    if let windowScene = scene as? UIWindowScene {
      let window = UIWindow(windowScene: windowScene)
      window.rootViewController = UIHostingController(rootView: profileView)
      self.window = window
      window.makeKeyAndVisible()
    }
  }
}

7. AppDelegate.swift

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate { }

8. User.swift

import Foundation

struct User: Hashable, Equatable {
  let name: String
  let imageURL: String
  let bio: String
  let area: String
  let friends: [User]
  let photos: [String]
  let historyFeed: [Post]

  static func == (lhs: User, rhs: User) -> Bool {
    lhs.name == rhs.name && lhs.imageURL == rhs.imageURL
  }
}

struct Post: Hashable {
  let pictureURL: String
  let message: String
  let likesCount: Int
  let commentsCount: Int
}

9. Mock.swift

import Foundation

enum Mock {
  static func user() -> User {
    return User(
      name: "Belle",
      imageURL: "https://images.unsplash.com/photo-1522593596038-8a7b75a0f2bc?ixlib=rb-1.2.1&auto=format&fit=crop&w=2250&q=80",
      bio: "I love hiking, exploring new countries and traditional dishes",
      area: "Italy",
      friends: friends(),
      photos: photos(),
      historyFeed: posts()
    )
  }

  static func photos() -> [String] {
    return [
      "https://images.unsplash.com/photo-1553808354-74b53671c8b4?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=300&q=80",
      "https://images.unsplash.com/photo-1570996915537-dd53ef642ef7?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=300&q=80",
      "https://images.unsplash.com/photo-1553808353-54724c294f0c?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=300&q=80",
      "https://images.unsplash.com/photo-1552396422-9d90144ceb97?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=300&q=80",
      "https://images.unsplash.com/photo-1573314481772-97f0b6102c17?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=300&q=80",
      "https://images.unsplash.com/photo-1586866928487-2af5b3850105?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=300&q=80"
    ]
  }

  static func posts() -> [Post] {
    return [
      Post(pictureURL: "https://images.unsplash.com/photo-1440186347098-386b7459ad6b?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=300&q=80", message: "", likesCount: 20, commentsCount: 10),
      Post(pictureURL: "https://images.unsplash.com/photo-1501554728187-ce583db33af7?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=300&q=80", message: "Such a nice view!", likesCount: 32, commentsCount: 5),
      Post(pictureURL: "https://images.unsplash.com/photo-1500049242364-5f500807cdd7?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=300&q=80", message: "", likesCount: 20, commentsCount: 10),
      Post(pictureURL: "https://images.unsplash.com/photo-1442570468985-f63ed5de9086?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=300&q=80", message: "", likesCount: 20, commentsCount: 10),
      Post(pictureURL: "https://images.unsplash.com/photo-1574325298943-eacd397f382d?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=300&q=80", message: "I love train rides", likesCount: 20, commentsCount: 10),
      Post(pictureURL: "https://images.unsplash.com/photo-1549872178-96db16a53ca8?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=300&q=80", message: "Ready for a new adventure", likesCount: 20, commentsCount: 10)
    ]
  }

  static func friends() -> [User] {
    return [
      User(name: "Leila", imageURL: "https://images.unsplash.com/photo-1474073705359-5da2a8270c64?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=300&q=80", bio: "", area: "", friends: [], photos: [], historyFeed: []),
      User(name: "Ingrid", imageURL: "https://images.unsplash.com/photo-1520512202623-51c5c53957df?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=300&q=80", bio: "", area: "", friends: [], photos: [], historyFeed: []),
      User(name: "Leon", imageURL: "https://images.unsplash.com/photo-1534614971-6be99a7a3ffd?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=300&q=80", bio: "", area: "", friends: [], photos: [], historyFeed: []),
      User(name: "Jonathan", imageURL: "https://images.unsplash.com/photo-1484517186945-df8151a1a871?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=300&q=80", bio: "", area: "", friends: [], photos: [], historyFeed: []),
      User(name: "Jay", imageURL: "https://images.unsplash.com/photo-1485361767769-5ceffc9f2144?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=300&q=80", bio: "", area: "", friends: [], photos: [], historyFeed: []),
      User(name: "Harriette", imageURL: "https://images.unsplash.com/photo-1468817814611-b7edf94b5d60?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=300&q=80", bio: "", area: "", friends: [], photos: [], historyFeed: [])
    ]
  }
}

10. ImageLoader.swift

import Combine
import SwiftUI

class ImageLoader: ObservableObject {
  var didChange = PassthroughSubject<UIImage, Never>()
  var image = UIImage() {
    didSet {
      didChange.send(image)
    }
  }

  init(urlString: String) {
    guard let url = URL(string: urlString) else { return }
    let task = URLSession.shared.dataTask(with: url) { data, _, _ in
      guard let data = data else { return }
      DispatchQueue.main.async {
        self.image = UIImage(data: data) ?? UIImage()
      }
    }
    task.resume()
  }
}

11. PrivacySetting.swift

enum PrivacySetting: String, CaseIterable {
  case photos = "Who can see my photos",
  friends = "Who can see my friends list",
  feed = "Who can see my feed",
  videoCall = "Who can video call me",
  message = "Who can message me"
}

12. ProfileContentProvider.swift

import SwiftUI
import Combine

protocol ProfileContentProviderProtocol: ObservableObject {
  var privacyLevel: PrivacyLevel { get }
  var canSendMessage: Bool { get }
  var canStartVideoChat: Bool { get }
  var photosView: AnyView { get }
  var feedView: AnyView { get }
  var friendsView: AnyView { get }
}

final class ProfileContentProvider<Store>: ProfileContentProviderProtocol where Store: PreferencesStoreProtocol {
  let privacyLevel: PrivacyLevel
  private let user: User
  private var store: Store
  private var cancellables: Set<AnyCancellable> = []

  init(
    // swiftlint:disable force_unwrapping
    privacyLevel: PrivacyLevel = DIContainer.shared.resolve(type: PrivacyLevel.self)!,
    user: User = DIContainer.shared.resolve(type: User.self)!,
    store: Store = DIContainer.shared.resolve(type: Store.self)!
    // swiftlint:enable force_unwrapping
  ) {
    self.privacyLevel = privacyLevel
    self.user = user
    self.store = store

    store.objectWillChange.sink { _ in
      self.objectWillChange.send()
    }
    .store(in: &cancellables)
  }

  var canSendMessage: Bool {
    privacyLevel >= store.messagePreference
  }

  var canStartVideoChat: Bool {
    privacyLevel >= store.videoCallsPreference
  }

  var photosView: AnyView {
    privacyLevel >= store.photosPreference ? AnyView(PhotosView(photos: user.photos)) : AnyView(EmptyView())
  }

  var feedView: AnyView {
    privacyLevel >= store.feedPreference ? AnyView(HistoryFeedView(posts: user.historyFeed)) : AnyView(EmptyView())
  }

  var friendsView: AnyView {
    privacyLevel >= store.friendsListPreference ?
      AnyView(UsersView(title: "Friends", users: user.friends)) :
      AnyView(EmptyView())
  }
}

13. DIContainer.swift

import Foundation

protocol DIContainerProtocol {
  func register<Component>(type: Component.Type, component: Any)
  func resolve<Component>(type: Component.Type) -> Component?
}

final class DIContainer: DIContainerProtocol {
  static let shared = DIContainer()

  private init() {}

  var components: [String: Any] = [:]

  func register<Component>(type: Component.Type, component: Any) {
    components["\(type)"] = component
  }

  func resolve<Component>(type: Component.Type) -> Component? {
    return components["\(type)"] as? Component
  }
}

后记

本篇主要讲述了基于SwiftUI简单App的Dependency Injection应用，感兴趣的给个赞或者关注~~~

SwiftUI框架详细解析（十七） —— 基于SwiftUI简

版本记录

前言

源码

1. Swift

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