#Xcode tutorial post json how to#
#Xcode tutorial post json software#
#Xcode tutorial post json code#

The syntax is given below.Ĭlass ViewController: UIViewController weak var tableView: UITableView! It returns the value of the type we specify, decoded from a JSON object. The decode method of JSONDecoder is used to decode the JSON response. To parse the response in Alamofire API request, we will use JSONDecoder, which is an object that decodes instances of a data type from JSON objects. Public var collectionExplicitness : String? Creating a mapping between a model type and the corresponding JSON dataĪs a start, let’s grab some JSON data representing a launch from the API.Public var collectionCensoredName : String?

#Xcode tutorial post json code#

You can find the code for the whole app on GitHub. While small, this app will cover all the common cases you find when decoding JSON data. One that shows a list of SpaceX rocket launches, and one that shows the detail of a selected launch.

We will build a small app with two screens.

This article uses v3, but it makes no difference to the concepts I’ll be explaining. Since I published this article, a new version (v4) has been introduced. Luckily, I found this handy list of public APIs, where we have plenty to choose from.įor this article, I will use the SpaceX API. To see a practical example, we need some JSON data and, ideally, a remote API that provides it. It is quite common to start from the last step and proceed backward, which is what we will do in this article. You don’t have to write your code in this order necessarily. Map the JSON data to your model types by making them conform to the Decodable protocol.Feed the data you receive to a JSONDecoder instance.Perform a network request to fetch the data.In any app, you have to go through three steps to decode the JSON data you get from a REST API. The three-step process to decode JSON data in Swift If you need to do both, you can use the Codable typealias instead, which is just a combination of the other two protocols.Īll the encoding and decoding code gets generated automatically for you by the Swift compiler.Īnd while the Codable protocols are often used for JSON decoding, they also work for other formats, like, for example, property lists. When you want to decode or encode some JSON data, the corresponding model types in your project need to conform to the Decodable and Encodable protocols respectively. So, when the Codable protocols were introduced, I was quite pleased to see that they force you to put transformation code into model types. This allows you to keep view controllers lean and avoid massive view controllers. I have been for a long time an advocate of putting transformation code into model types. Since an app has to deal with an internal and an external representation of its data, we need some code to convert from one to the other, and vice-versa. Where you should put the code to encode and decode JSON data

So, most REST APIs return data in JSON format. JSON is the most popular of the two because it has a simpler structure that can be efficiently encoded and decoded. In today’s internet, the two most popular formats to represent data are JSON and XML. To allow communication, we need a standard format understood by applications written in different languages.

For that, we need an external representation of our data.

#Xcode tutorial post json software#

Software often stores data permanently and communicates with other software. That is the app’s internal representation of its data. In MVC, we represented data in the model layer, where we use structures and enumerations to represent data entities and their business logic. In iOS, we develop apps following the MVC pattern. So we need a way to represent it and its business logic in code. The relationship between JSON data and the model types in your appīefore we get into the nitty-gritty of decoding, we need to clarify the relationship between code and data.Īny iOS app needs to deal with data. After mapping data to Swift types, you can easily decode data in a few lines of code.

#Xcode tutorial post json how to#

The first thing you need to take care of when decoding JSON data is how to represent it in your app using Swift types.