Apple recommends MVC architecture for development and is undeniably more common architecture. MVC segregate code in three parts — logic/data, view(GUI) and model. Today we’ll talk about how to write models while minimising boilerplate code.

苹果公司推荐使用MVC架构进行开发，并且毫无疑问，它是更常见的架构。 MVC将代码分为三部分-逻辑/数据，视图(GUI)和模型。 今天，我们将讨论如何在最小化样板代码的同时编写模型。

Models are representations of data that flows through your application. For example, we get unordered and unreadable junk from servers and that too in huge quantity. We know we have some edible data in the junk and we need a way to filter it out. Moreover model has knowledge of a domain(say User), user’s data is used multiple times in an application. Same user model can be used at all places.

模型是流经您的应用程序的数据的表示。 例如，我们从服务器中收到无序且难以读取的垃圾，并且数量也很大。 我们知道垃圾中有一些可食用的数据，我们需要一种过滤数据的方法。 而且模型具有领域知识(比如说用户)，用户的数据在应用程序中被多次使用。 可以在所有地方使用相同的用户模型。

Models are not concerned about UI and presentation of data and not even the logic behind operations. In simple words they are data containers, having data organised as objects with some properties. The view and the controller communicate with each other indirectly through these data containers(model).

模型不关心UI和数据表示，甚至不关心操作背后的逻辑。 简而言之，它们是数据容器，将数据组织为具有某些属性的对象。 视图和控制器通过这些数据容器(模型)间接相互通信。

To understand it better let’s have an eye on some code.

为了更好地理解它，让我们看一些代码。

Lets create a demo JSON having with object named organisation and having three associated properties

让我们创建一个演示JSON ，该JSON具有名为organization的对象并具有三个关联的属性

{"organization" : {"organization_name" : "XYZ Enterprises","organization_location" : "Lucknow, India","established_year":2012}
}

We will parse the JSON first using the conventional model approach. Next, we do the same task using Codable.

我们将首先使用常规模型方法解析JSON。 接下来，我们使用Codable执行相同的任务。

老派方法 (Old School Approach)

Consider a model named Organization with some properties:

考虑一个名为Organization的模型，该模型具有一些属性：

class Organization {orgName: StringorgLocation: Stringestablished: Int}

Organisation has three properties — orgName of String type, orgLocation is again of String type. and established year of Integer type.

Organisation有三个属性- orgName的String类型， orgLocation又是String类型。 并established Integer类型的年份。

Organisation properties has to be initialised. We will initialise it using init() method:

组织属性必须初始化。 我们将使用init()方法对其进行init() ：

class Organization {
orgName: String
orgLocation: String
established: Intinit?(orgName: String, orgLocation: String, established: Int) {// Initialize stored properties.
self.orgName = orgName
self.orgLocation = orgLocation
self.established = established}
}

Let’s see a use case of model: Let suppose we have response in JSON format from the server. We first have to parse JSON and set it in our model class.

让我们看一下模型的用例：假设我们有来自服务器的JSON格式的响应。 我们首先必须解析JSON并将其设置在模型类中。

var organization: Organization?
let jsonData: Data = /* get your json data from server or local json file */
let jsonArray = try [JSONSerialization.jsonObject(with: jsonData) as? [NSDictionary] let organizationName = jsonArray["organization_name"] as? String
let organizationLocation = jsonArray["organization_location"] as? String
let established = jsonArray["established_year"] as? Int
user(orgName: organizationName, orgLocation: organizationLocation, age: established)

That’s general way parsing json in models.Now will do the same task but now using codable and will talk about the differences between these two approaches.

这是解析模型中json的一般方法，现在将执行相同的任务，但现在使用可codable ，并将讨论这两种方法之间的差异。

使用可编码的更清洁方法 (Cleaner Approach using codable)

Codable is collective name given to protocols Encodable and decodable. In this demo we only need decodable. We write codable model as follows:

Codable是协议可编码和可解码的总称。 在此演示中，我们只需要可解码的即可。 我们编写可codable模型如下：

And thats it!.Here, names of the parameters matches the json keys. If you want to follow your favourite naming convention then you can use coding keys. Coding keys helps you keep your code readable. You can implement coding keys like this

就是这样！。在这里，参数名称与json键匹配。 如果要遵循自己喜欢的命名约定，则可以使用编码键。 编码键可帮助您保持代码的可读性。 您可以像这样实现编码键

Now we will decode json data.

现在我们将解码json数据。

let jsonData: Data = /* get your json data from server or local json file */
let organization = JSONDecoder().decode(Organization.self, from: jsonData)
print("Organization Name: - \(organization.orgName) \n")
print("Organization location: - \(organization.orgName) \n")
print("Year of foundation: - \(organization.established)")

Above snippet simply prints parsed data on console. The output looks like this

以上代码段仅在控制台上打印已解析的数据。 输出看起来像这样

Organization Name: - XYZ Enterprises
Organization location - Lucknow, India
Year of foundation: - 2012

Decodable, clearly is winner if we compare above two approaches of JSON parsing.

如果我们比较上述两种JSON解析方法，那么Decodable显然是赢家。

!!! HAPPY CODING !!!

!!! 快乐编码！

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