开始用Swift开发iOS 10 - 11 面向对象编程介绍

关于面向对象编程（Object Oriented Programming ，OOP）的知识就不多介绍了，这不是一门编程语言中的概念，而是编程方法。OOP最好的一地方是，它让复杂的软件分解成一个个小的部分，方便程序员开放和管理。

这一篇文章就把上一篇文章开始用Swift开发iOS 10 - 10 Navigation Controller的介绍和Segue的代码整理成OOP形式。

重新修改FoodPin项目

• 之前在RestaurantTableViewController类中，定义了restaurantNames,restaurantImages, restaurantLocations,restaurantTypes四个数组变量，分别表示restaurant的名字，图片名称，位置，类型。每个restaurant的信息分散在四个数组中，而且数组的内容顺序要对应，现在把四个信息组成在一个类中Restaurant。

• 添加类文件Restaurant.swift

  import Foundation
  
  class Restaurant {
      var name = ""
      var type = ""
      var location = ""
      var image = ""
      var isVisited = false
      // 1
      init(name: String, type: String, location: String, image: String,
           isVisited: Bool) {
          self.name = name
          self.type = type
          self.location = location
          self.image = image
          self.isVisited = isVisited
      }
  }

  • 1 自定义的初始化方法。在Swift中，类的所有变量都需要被初始化，或者声明为可选值。

• 用Restaurant对象数组代替RestaurantTableViewController中的几个数组变量。

  var restaurants:[Restaurant] = [
    Restaurant(name: "Cafe Deadend", type: "Coffee & Tea Shop", location: "HongKong", image: "cafedeadend.jpg", isVisited: false),
    Restaurant(name: "Homei", type: "Cafe", location: "Hong Kong", image:"homei.jpg", isVisited: false),
    Restaurant(name: "Teakha", type: "Tea House", location: "Hong Kong", image:"teakha.jpg", isVisited: false),
    Restaurant(name: "Cafe loisl", type: "Austrian / Causual Drink", location: "Hong Kong", image: "cafeloisl.jpg", isVisited: false),
    Restaurant(name: "Petite Oyster", type: "French", location: "Hong Kong", image: "petiteoyster.jpg", isVisited: false),
    Restaurant(name: "For Kee Restaurant", type: "Bakery", location: "HongKong", image: "forkeerestaurant.jpg", isVisited: false),
    Restaurant(name: "Po's Atelier", type: "Bakery", location: "Hong Kong", image: "posatelier.jpg", isVisited: false),
    Restaurant(name: "Bourke Street Backery", type: "Chocolate", location: "Sydney", image: "bourkestreetbakery.jpg", isVisited: false),
    Restaurant(name: "Haigh's Chocolate", type: "Cafe", location: "Sydney", image: "haighschocolate.jpg", isVisited: false),
    Restaurant(name: "Palomino Espresso", type: "American / Seafood", location: "Sydney", image: "palominoespresso.jpg", isVisited: false),
    Restaurant(name: "Upstate", type: "American", location: "New York", image: "upstate.jpg", isVisited: false),
    Restaurant(name: "Traif", type: "American", location: "New York", image: "traif.jpg", isVisited: false),
    Restaurant(name: "Graham Avenue Meats", type: "Breakfast & Brunch", location: "New York", image: "grahamavenuemeats.jpg", isVisited: false),
    Restaurant(name: "Waffle & Wolf", type: "Coffee & Tea", location: "NewYork", image: "wafflewolf.jpg", isVisited: false),
    Restaurant(name: "Five Leaves", type: "Coffee & Tea", location: "New York",image: "fiveleaves.jpg", isVisited: false),
    Restaurant(name: "Cafe Lore", type: "Latin American", location: "New York", image: "cafelore.jpg", isVisited: false),
    Restaurant(name: "Confessional", type: "Spanish", location: "New York", image: "confessional.jpg", isVisited: false),
    Restaurant(name: "Barrafina", type: "Spanish", location: "London", image: "barrafina.jpg", isVisited: false),
    Restaurant(name: "Donostia", type: "Spanish", location: "London", image: "donostia.jpg", isVisited: false),
    Restaurant(name: "Royal Oak", type: "British", location: "London", image: "royaloak.jpg", isVisited: false),
    Restaurant(name: "CASK Pub and Kitchen", type: "Thai", location: "London", image: "caskpubkitchen.jpg", isVisited: false)
  ]
  

• 更新 tableView(_:numberOfRowsInSection:) :

  override func tableView(_ tableView: UITableView, numberOfRowsInSection
  section: Int) -> Int {
      return restaurants.count
  }

• 更新 tableView(_:cellForRowAtIndexPath:) ：

  override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
      let cellIdentifier = "Cell"
      let cell = tableView.dequeueReusableCell(withIdentifier: cellIdentifier,
                                               for: indexPath) as! RestaurantTableViewCell
      // Configure the cell...
      cell.nameLabel.text = restaurants[indexPath.row].name
      cell.thumbnailImageView.image = UIImage(named: restaurants[indexPath.row].image)
      cell.thumbnailImageView.layer.cornerRadius = 30.0
      cell.thumbnailImageView.clipsToBounds = true
      cell.locationLabel.text = restaurants[indexPath.row].location
      cell.typeLabel.text = restaurants[indexPath.row].type
      
      cell.accessoryType = restaurants[indexPath.row].isVisited ? .checkmark : .none
      
      return cell
  }

• 更新tableView(_:commit:forRowAt:) :

  override func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
      if editingStyle == .delete {
          restaurants.remove(at: indexPath.row)
      }
      tableView.deleteRows(at: [indexPath], with: .fade)
  }

• 更新 tableView(_:editActionsForRowAt:) ：

  override func tableView(_ tableView: UITableView, editActionsForRowAt indexPath: IndexPath) -> [UITableViewRowAction]? {
  
      let shareAction = UITableViewRowAction(style: .default, title: "Share", handler: {
          (action, indexPath) -> Void in
  
          let defaultText = "Just checking in at " + self.restaurants[indexPath.row].name
          if let imageToShare = UIImage(named: self.restaurants[indexPath.row].image) {
              let activityController = UIActivityViewController(activityItems: [defaultText, imageToShare], applicationActivities: nil)
              self.present(activityController, animated: true, completion: nil)
          }
  
      })
  
      let deleteAction = UITableViewRowAction(style: .default, title: "Delete", handler: {
          (action, indexPath) -> Void in
  
          self.restaurants.remove(at: indexPath.row)
  
          tableView.deleteRows(at: [indexPath], with: .fade)
      })
  
      shareAction.backgroundColor = UIColor(red: 48.0/255.0, green: 173.0/255.0,
                                            blue: 99.0/255.0, alpha: 1.0)
      deleteAction.backgroundColor = UIColor(red: 202.0/255.0, green: 202.0/255.0,
                                             blue: 203.0/255.0, alpha: 1.0)
  
      return [deleteAction,shareAction]
  }
  

• RestaurantDetailViewController中的四个变量：

  var nameText = ""
  var locationText = ""
  var typeText = ""
  var restaurantImage = ""

  更新为：var restaurant: Restaurant!

  与之对应的viewDidLoad()也修改为：

  override func viewDidLoad() {
      super.viewDidLoad()
  
      restaurantImageView.image = UIImage(named: restaurant.image)
      nameLabel.text = restaurant.name
      locationLabel.text = restaurant.location
      typeLabel.text = restaurant.type
  }
  

• 最后prepare(for:sender:)方法也做对应修改：

  override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
      if segue.identifier == "showRestaurantDetail" {
          if let indexPath = tableView.indexPathForSelectedRow {
              let destinationController = segue.destination as! RestaurantDetailViewController
              destinationController.restaurant = restaurants[indexPath.row]
          }
      }
  }

运行没有问题。

代码

Beginning-iOS-Programming-with-Swift

说明

此文是学习appcode网站出的一本书 《Beginning iOS 10 Programming with Swift》 的一篇记录