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。
  • 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

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