我在 CoreData 模型中有两个实体(产品和图像)，产品(一个)-图像(多个)之间存在一对多关系。我还对我的实体进行了子类化，并且我正在尝试从 json 文件填充数据库；但是我似乎无法理解如何将图像插入到与产品相关的图像中，因此当我在应用程序中选择该产品时，我会获得所有相关图像。

extension Products {
    @NSManaged var price: NSNumber?
    @NSManaged var stock: NSNumber?
    @NSManaged var desc: String?
    @NSManaged var name: String?
    @NSManaged var images: NSSet?
    @NSManaged var sales: NSSet?
}

extension Images {
    @NSManaged var image: String?
    @NSManaged var products: Products?
}

然后是 json 文件数据(我用 NSJSONObjectWithData 序列化它没有任何问题:

{ "records" : [{ "name" : "Apple iMac 27in", "description" : "The stunning all-in-one iMac features a beautiful 27-inch Retina 5K widescreen display, quad-core Intel Core i5 processors and AMD Radeon R9 M380 graphics processor with 2GB of GDDR5 memory.", "image" : ["imac1.jpg", "imac2.jpg"], "stock" : 32, "price" : 1699.00 }, { "name" : "Apple iPhone 6s Plus 128 GB", "description" : "The moment you use iPhone 6s Plus, you know you’ve never felt anything like it. With just a single press, 3D Touch lets you do more than ever before. Live Photos bring your memories to life in a powerfully vivid way. And that’s just the beginning. Take a deeper look at iPhone 6s Plus, and you’ll find innovation on every level.", "image" : ["iphone6splus1.jpg", "iphone6splus2.jpg", "iphone6splus3.jpg", "iphone6splus4.jpg"], "stock" : 144, "price" : 1042.00 } ]}

这是我在检查数据库是否为空后用于在 AppDelegate 中填充数据库的函数。

func fillDatabase() {
    let jsonURL = NSBundle.mainBundle().URLForResource("products", withExtension: "json");
    let data = NSData(contentsOfURL: jsonURL!);
    do {
        let jsonData = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions(rawValue: 0)) as! Dictionary<String, AnyObject>;
        let recordset = jsonData["records"] as! Array<Dictionary<String, AnyObject>>;
        for record in recordset {
            let product = Products(context: managedObjectContext);

            if let name = record["name"] {
                product.name = name as? String;
            }

            if let stock = record["stock"] as? NSNumber {
                product.stock = stock;
            }

            if let price = record["price"] as? Double {
                product.price = price;
            }

            if let desc = record["description"] as? String {
                product.desc = desc;
            }

            if let images = record["image"] as? NSMutableArray {    
                // *********************************************************
                // Im getting the array of images, but dont know where to go from here.
            }

            do {
                try managedObjectContext.save();
            } catch let error as NSError {
                print(error.debugDescription);
            }
        }
    } catch let error as NSError {
        print("error parsing json object:  \(error.debugDescription)");
        return;
    }
}

最佳答案

鉴于您在 Core Data 中正确设置了关系，您应该能够使用如下方式关联图像:

product.images = NSSet(array: imageArray)

确保 imageArray 变量包含 Images 类型的对象。

总而言之，首先您需要解析数组并从该数组创建Images 产品:

var imageArray = [Images]()

for yourRawImageFromJSON in json{
    let image1 = Images(context: managedObjectContext)
    // set properties on image
    yourImages.append(image1)
}

然后，一旦你有了 Images 数组，就按照我上面说的去做(为了完整起见再次在这里添加它):

product.images = NSSet(array: imageArray)

旁注

您应该遵循以单数格式命名类的一般规则，因此不要使用 Images 和 Products 作为您的类名，您应该使用 Image 和 Product。尽管一个类代表一个广义的概念(很像在数据库系统中，概念类以复数形式命名)，但使用单数形式更常见也更方便(例如使用 let product = Product 更简洁() 而不是 let product = Products() 因为后者传达了您正在实例化多个实例的概念，尽管显然不是这种情况)

关于ios - 将值插入 CoreData 中的相关实体，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/35782966/