Question

我只是尝试在Swift中进行编码，并且尝试在Apple Dev Library re：Meals中修改此现有项目。

我希望将其他子类（例如“成分”）放到主餐类中，将其作为数组或成分。

import UIKit
import os.log

class Meal: NSObject, NSCoding {

    //MARK: Properties

    var name: String
    var photo: UIImage?
    var rating: Int
    var recipe: [ingredients]?

    //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"
        static let recipe = "recipe"
    }

    //MARK: Initialization

    init?(name: String, photo: UIImage?, rating: Int, recipe: ingredients!) {

        // The name must not be empty
        guard !name.isEmpty else {
            return nil
        }

        // The rating must be between 0 and 5 inclusively
        guard (rating >= 0) && (rating <= 5) else {
            return nil
        }

        // Initialization should fail if there is no name or if the rating is negative.
        if name.isEmpty || rating < 0  {
            return nil
        }

        // Initialize stored properties.
        self.name = name
        self.photo = photo
        self.rating = rating
        self.recipe = recipe
    }

    //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)
        aCoder.encode(recipe, forKey: PropertyKey.recipe)
    }

    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)

        let recipe = aDecoder.decodeObject(forKey: PropertyKey.recipe)

        // Must call designated initializer.
        self.init(name: name, photo: photo, rating: rating, recipe: recipe)

    }
}

用于保存和加载膳食项目的函数调用如下：

   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]
    }

我声明了一个新的Class Ingredients.swift来捕获我想要的成分。

import UIKit
import os.log

class Ingredients: NSObject {

    struct PropertyKey {
        static let name = "name"
        static let  quantity = "quantity"
    }

    var name: String!
    var quantity: Double!

    //MARK: Initialization

    init?(name: Int, quantity: Double) {

        self.name = name
        self.quantity = quantity
    }
}

我现在遇到的问题是XCode抛出“由于未捕获的异常而正在终止应用程序

“ NSInvalidArgumentException”，原因：“-[MealTracker.Ingredients encodeWithCoder：]：无法识别的选择器已发送到实例 0x1c40a0e40'“

我能知道如何成功地将Ingredients数组包含到保存的对象中吗？

Answer 1

您必须实现NSCoding协议

func encode(with aCoder: NSCoder) {}
required convenience init?(coder aDecoder: NSCoder) {}

还在内部自定义类中

class Ingredients: NSObject , NSCoding {}

如何在Swift IOS中使用NSKeyedArchiver保存带有子类的对象

1 个答案: