Persists Data

iOSTemplate/Meal.swift

@@ -6,13 +6,27 @@
 //
 
 import UIKit
+import os.log
 
-class Meal {
+class Meal: NSObject, NSCoding {
     // MARK: Properties
     
     var name: String
     var photo: UIImage?
     var rating: Int
+    
+    // MARK: Archiving Paths
+    
+    static let DocumentsDirectory = FileManager().urls(for: .documentDirectory, in: .userDomainMask).first!
+    static let ArchiveURL = DocumentsDirectory.appendingPathComponent("meals")
+    
+    // MARK: Types
+    
+    struct PropertyKey {
+        static let name = "name"
+        static let photo = "photo"
+        static let rating = "rating"
+    }
  
     // MARK: Initialization
     
@@ -32,4 +46,29 @@ class Meal {
         self.photo = photo
         self.rating = rating
     }
+    
+    // MARK: NSCoding
+    
+    func encode(with aCoder: NSCoder) {
+        aCoder.encode(name, forKey: PropertyKey.name)
+        aCoder.encode(photo, forKey: PropertyKey.photo)
+        aCoder.encode(rating, forKey: PropertyKey.rating)
+    }
+    
+    required convenience init?(coder aDecoder: NSCoder) {
+        // The name is required. If we cannot decode a name string, the initializer should fail.
+        guard let name = aDecoder.decodeObject(forKey: PropertyKey.name) as? String else {
+            os_log("Unable to decode the name for a Meal object.", log: OSLog.default, type: .debug)
+            return nil
+        }
+        
+        // Because photo is an optional property of Meal, just use conditional cast.
+        let photo = aDecoder.decodeObject(forKey: PropertyKey.photo) as? UIImage
+        
+        let rating = aDecoder.decodeInteger(forKey: PropertyKey.rating)
+        
+        // Must call designated initializer.
+        self.init(name: name, photo: photo, rating: rating)
+    }
+    
 }

iOSTemplate/MealTableViewController.swift

@@ -19,8 +19,14 @@ class MealTableViewController: UITableViewController {
         // Use the edit button item provided by the table view controller.
         navigationItem.leftBarButtonItem = editButtonItem
 
-        // Load the sample data.
-        loadSampleMeals()
+        // Load any saved meals, otherwise load sample data.
+        if let savedMeals = loadMeals() {
+            meals += savedMeals
+        }
+        else {
+            // Load the sample data.
+            loadSampleMeals()
+        }
     }
 
     // MARK: - Table view data source
@@ -61,6 +67,7 @@ class MealTableViewController: UITableViewController {
         if editingStyle == .delete {
             // Delete the row from the data source
             meals.remove(at: indexPath.row)
+            saveMeals()
             tableView.deleteRows(at: [indexPath], with: .fade)
         } else if editingStyle == .insert {
             // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
@@ -118,6 +125,7 @@ class MealTableViewController: UITableViewController {
     
     @IBAction func unwindToMealList(sender: UIStoryboardSegue) {
         if let sourceViewController = sender.source as? MealViewController, let meal = sourceViewController.meal {
+            
             if let selectedIndexPath = tableView.indexPathForSelectedRow {
                 // Update an existing meal.
                 meals[selectedIndexPath.row] = meal
@@ -130,6 +138,9 @@ class MealTableViewController: UITableViewController {
                 meals.append(meal)
                 tableView.insertRows(at: [newIndexPath], with: .automatic)
             }
+            
+            // Save the meals.
+            saveMeals()
         }
     }
 
@@ -154,4 +165,17 @@ class MealTableViewController: UITableViewController {
         
         meals += [meal1, meal2, meal3]
     }
+    
+    private func saveMeals() {
+        let isSuccessfulSave = NSKeyedArchiver.archiveRootObject(meals, toFile: Meal.ArchiveURL.path)
+        if isSuccessfulSave {
+            os_log("Meals successfully saved.", log: OSLog.default, type: .debug)
+        } else {
+            os_log("Failed to save meals...", log: OSLog.default, type: .error)
+        }
+    }
+    
+    private func loadMeals() -> [Meal]?  {
+        return NSKeyedUnarchiver.unarchiveObject(withFile: Meal.ArchiveURL.path) as? [Meal]
+    }
 }