版本记录

版本号	时间
V1.0	2019.02.01 星期五

前言

Firebase是一家实时后端数据库创业公司，它能帮助开发者很快的写出Web端和移动端的应用。自2014年10月Google收购Firebase以来，用户可以在更方便地使用Firebase的同时，结合Google的云服务。Firebase能让你的App从零到一。也就是说它可以帮助手机以及网页应用的开发者轻松构建App。通过Firebase背后负载的框架就可以简单地开发一个App，无需服务器以及基础设施。接下来几篇我们就一起看一下基于Firebase平台的开发。感兴趣的看下面几篇文章。
1. 基于Firebase平台开发（一） —— 基于ML Kit的iOS图片中文字的识别（一）
2. 基于Firebase平台开发（二） —— 基于ML Kit的iOS图片中文字的识别（二）
3. 基于Firebase平台开发（三） —— Firebase基本使用简介（一）
4. 基于Firebase平台开发（四） —— Firebase基本使用简介（二）

源码

1. Swift

首先看下工程结构

接着看下sb中的内容

下面就是一起看代码

1. GroceryItem.swift

import Foundation
import Firebase

struct GroceryItem {
  
  let ref: DatabaseReference?
  let key: String
  let name: String
  let addedByUser: String
  var completed: Bool
  
  init(name: String, addedByUser: String, completed: Bool, key: String = "") {
    self.ref = nil
    self.key = key
    self.name = name
    self.addedByUser = addedByUser
    self.completed = completed
  }
  
  init?(snapshot: DataSnapshot) {
    guard
      let value = snapshot.value as? [String: AnyObject],
      let name = value["name"] as? String,
      let addedByUser = value["addedByUser"] as? String,
      let completed = value["completed"] as? Bool else {
      return nil
    }
    
    self.ref = snapshot.ref
    self.key = snapshot.key
    self.name = name
    self.addedByUser = addedByUser
    self.completed = completed
  }
  
  func toAnyObject() -> Any {
    return [
      "name": name,
      "addedByUser": addedByUser,
      "completed": completed
    ]
  }
}

2. User.swift

import Foundation
import Firebase

struct User {
  
  let uid: String
  let email: String
  
  init(authData: Firebase.User) {
    uid = authData.uid
    email = authData.email!
  }
  
  init(uid: String, email: String) {
    self.uid = uid
    self.email = email
  }
}

3. GroceryListTableViewController.swift

import UIKit
import Firebase

class GroceryListTableViewController: UITableViewController {

  // MARK: Constants
  let listToUsers = "ListToUsers"
  
  // MARK: Properties
  var items: [GroceryItem] = []
  var user: User!
  var userCountBarButtonItem: UIBarButtonItem!
  let ref = Database.database().reference(withPath: "grocery-items")
  let usersRef = Database.database().reference(withPath: "online")
  
  override var preferredStatusBarStyle: UIStatusBarStyle {
    return .lightContent
  }
  
  // MARK: UIViewController Lifecycle  
  override func viewDidLoad() {
    super.viewDidLoad()
    
    tableView.allowsMultipleSelectionDuringEditing = false
    
    userCountBarButtonItem = UIBarButtonItem(title: "1",
                                             style: .plain,
                                             target: self,
                                             action: #selector(userCountButtonDidTouch))
    userCountBarButtonItem.tintColor = UIColor.white
    navigationItem.leftBarButtonItem = userCountBarButtonItem
    
    ref.queryOrdered(byChild: "completed").observe(.value, with: { snapshot in
      var newItems: [GroceryItem] = []
      for child in snapshot.children {
        if let snapshot = child as? DataSnapshot,
          let groceryItem = GroceryItem(snapshot: snapshot) {
          newItems.append(groceryItem)
        }
      }
      
      self.items = newItems
      self.tableView.reloadData()
    })
    
    Auth.auth().addStateDidChangeListener { auth, user in
      guard let user = user else { return }
      self.user = User(authData: user)
      
      let currentUserRef = self.usersRef.child(self.user.uid)
      currentUserRef.setValue(self.user.email)
      currentUserRef.onDisconnectRemoveValue()
    }
    
    usersRef.observe(.value, with: { snapshot in
      if snapshot.exists() {
        self.userCountBarButtonItem?.title = snapshot.childrenCount.description
      } else {
        self.userCountBarButtonItem?.title = "0"
      }
    })
  }
  
  // MARK: UITableView Delegate methods
  override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return items.count
  }
  
  override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "ItemCell", for: indexPath)
    let groceryItem = items[indexPath.row]
    
    cell.textLabel?.text = groceryItem.name
    cell.detailTextLabel?.text = groceryItem.addedByUser
    
    toggleCellCheckbox(cell, isCompleted: groceryItem.completed)
    
    return cell
  }
  
  override func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
    return true
  }
  
  override func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
    if editingStyle == .delete {
      let groceryItem = items[indexPath.row]
      groceryItem.ref?.removeValue()
    }
  }
  
  override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    guard let cell = tableView.cellForRow(at: indexPath) else { return }
    let groceryItem = items[indexPath.row]
    let toggledCompletion = !groceryItem.completed
    toggleCellCheckbox(cell, isCompleted: toggledCompletion)
    groceryItem.ref?.updateChildValues([
      "completed": toggledCompletion
      ])
  }
  
  func toggleCellCheckbox(_ cell: UITableViewCell, isCompleted: Bool) {
    if !isCompleted {
      cell.accessoryType = .none
      cell.textLabel?.textColor = .black
      cell.detailTextLabel?.textColor = .black
    } else {
      cell.accessoryType = .checkmark
      cell.textLabel?.textColor = .gray
      cell.detailTextLabel?.textColor = .gray
    }
  }
  
  // MARK: Add Item  
  @IBAction func addButtonDidTouch(_ sender: AnyObject) {
    let alert = UIAlertController(title: "Grocery Item",
                                  message: "Add an Item",
                                  preferredStyle: .alert)
    
    let saveAction = UIAlertAction(title: "Save", style: .default) { _ in
      guard let textField = alert.textFields?.first,
        let text = textField.text else { return }
      

      let groceryItem = GroceryItem(name: text,
                                    addedByUser: self.user.email,
                                    completed: false)

      let groceryItemRef = self.ref.child(text.lowercased())
      
      groceryItemRef.setValue(groceryItem.toAnyObject())
    }
    
    let cancelAction = UIAlertAction(title: "Cancel",
                                     style: .cancel)
    
    alert.addTextField()
    
    alert.addAction(saveAction)
    alert.addAction(cancelAction)
    
    present(alert, animated: true, completion: nil)
  }
  
  @objc func userCountButtonDidTouch() {
    performSegue(withIdentifier: listToUsers, sender: nil)
  }
}

4. LoginViewController.swift

import UIKit
import Firebase

class LoginViewController: UIViewController {
  
  // MARK: Constants
  let loginToList = "LoginToList"
  
  // MARK: Outlets
  @IBOutlet weak var textFieldLoginEmail: UITextField!
  @IBOutlet weak var textFieldLoginPassword: UITextField!
  
  override var preferredStatusBarStyle: UIStatusBarStyle {
    return .lightContent
  }
  
  // MARK: UIViewController Lifecycle
  override func viewDidLoad() {
    super.viewDidLoad()
    
    Auth.auth().addStateDidChangeListener() { auth, user in
      if user != nil {
        self.performSegue(withIdentifier: self.loginToList, sender: nil)
        self.textFieldLoginEmail.text = nil
        self.textFieldLoginPassword.text = nil
      }
    }
  }
  
  // MARK: Actions
  @IBAction func loginDidTouch(_ sender: AnyObject) {
    guard
      let email = textFieldLoginEmail.text,
      let password = textFieldLoginPassword.text,
      email.count > 0,
      password.count > 0
      else {
        return
    }
    
    Auth.auth().signIn(withEmail: email, password: password) { user, error in
      if let error = error, user == nil {
        let alert = UIAlertController(title: "Sign In Failed",
                                      message: error.localizedDescription,
                                      preferredStyle: .alert)
        
        alert.addAction(UIAlertAction(title: "OK", style: .default))
        
        self.present(alert, animated: true, completion: nil)
      }
    }
  }
  
  @IBAction func signUpDidTouch(_ sender: AnyObject) {
    let alert = UIAlertController(title: "Register",
                                  message: "Register",
                                  preferredStyle: .alert)
    
    let saveAction = UIAlertAction(title: "Save", style: .default) { _ in
      
      let emailField = alert.textFields![0]
      let passwordField = alert.textFields![1]
      
      Auth.auth().createUser(withEmail: emailField.text!, password: passwordField.text!) { user, error in
        if error == nil {
          Auth.auth().signIn(withEmail: self.textFieldLoginEmail.text!,
                             password: self.textFieldLoginPassword.text!)
        }
      }
    }
    
    let cancelAction = UIAlertAction(title: "Cancel",
                                     style: .cancel)
    
    alert.addTextField { textEmail in
      textEmail.placeholder = "Enter your email"
    }
    
    alert.addTextField { textPassword in
      textPassword.isSecureTextEntry = true
      textPassword.placeholder = "Enter your password"
    }
    
    alert.addAction(saveAction)
    alert.addAction(cancelAction)
    
    present(alert, animated: true, completion: nil)
  }  
}

extension LoginViewController: UITextFieldDelegate {
  
  func textFieldShouldReturn(_ textField: UITextField) -> Bool {
    if textField == textFieldLoginEmail {
      textFieldLoginPassword.becomeFirstResponder()
    }
    if textField == textFieldLoginPassword {
      textField.resignFirstResponder()
    }
    return true
  }
}

5. OnlineUsersTableViewController.swift

import UIKit
import Firebase

class OnlineUsersTableViewController: UITableViewController {
  
  // MARK: Constants
  let userCell = "UserCell"
  
  // MARK: Properties
  var currentUsers: [String] = []
  let usersRef = Database.database().reference(withPath: "online")
  
  override var preferredStatusBarStyle: UIStatusBarStyle {
    return .lightContent
  }
  
  // MARK: UIViewController Lifecycle
  override func viewDidLoad() {
    super.viewDidLoad()
    usersRef.observe(.childAdded, with: { snap in
      guard let email = snap.value as? String else { return }
      self.currentUsers.append(email)
      let row = self.currentUsers.count - 1
      let indexPath = IndexPath(row: row, section: 0)
      self.tableView.insertRows(at: [indexPath], with: .top)
    })
    usersRef.observe(.childRemoved, with: { snap in
      guard let emailToFind = snap.value as? String else { return }
      for (index, email) in self.currentUsers.enumerated() {
        if email == emailToFind {
          let indexPath = IndexPath(row: index, section: 0)
          self.currentUsers.remove(at: index)
          self.tableView.deleteRows(at: [indexPath], with: .fade)
        }
      }
    })
  }
  
  // MARK: UITableView Delegate methods  
  override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return currentUsers.count
  }
  
  override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: userCell, for: indexPath)
    let onlineUserEmail = currentUsers[indexPath.row]
    cell.textLabel?.text = onlineUserEmail
    return cell
  }
  
  // MARK: Actions
  @IBAction func signoutButtonPressed(_ sender: AnyObject) {
    let user = Auth.auth().currentUser!
    let onlineRef = Database.database().reference(withPath: "online/\(user.uid)")
    onlineRef.removeValue { (error, _) in
      if let error = error {
        print("Removing online failed: \(error)")
        return
      }
      do {
        try Auth.auth().signOut()
        self.dismiss(animated: true, completion: nil)
      } catch (let error) {
        print("Auth sign out failed: \(error)")
      }
    }
  }
}

6. AppDelegate.swift

import UIKit
import Firebase

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
  
  var window: UIWindow?
  
  func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    FirebaseApp.configure()
    Database.database().isPersistenceEnabled = true
    return true
  }
}

这是年前最后一篇了，马上就要去坐火车回家了，回家就没条件写了，祝大家新年快乐，年后见！！

后记

本篇主要讲述了Firebase基本使用简介，感兴趣的给个赞或者关注~~~

基于Firebase平台开发（五） —— Firebase基本使用简介（三）

版本记录

前言

源码

1. Swift

后记

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