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As a beginner in SWIFT programming, you’ll often encounter the need to read and write JSON data. JSON (JavaScript Object Notation) is a lightweight data format that is commonly used to exchange data between different systems and services. In this article, we’ll introduce you to the basics of reading and writing JSON data in SWIFT.
What is JSON?
JSON is a data format that is commonly used to exchange data between different systems and services. It is a lightweight and human-readable format that is easy to work with. JSON is based on a simple data structure that consists of key-value pairs, similar to a dictionary in SWIFT.
For example, you might have a JSON object that represents a user, with key-value pairs for the user’s name, email address, and age. In JSON, this data would be represented as follows:
{ "name": "John Doe",
"email": "john.doe@example.com",
"age": 35
}
Reading JSON in SWIFT
To read JSON data in SWIFT, you can use the built-in JSONDecoder
class. The JSONDecoder
class allows you to parse JSON data into SWIFT objects. To use the JSONDecoder
class, you simply need to create an instance of the class and pass the JSON data to it. The JSONDecoder
class will then parse the JSON data and return a SWIFT object that you can work with.
For example, if you have the following JSON data:
{ "name": "John Doe", "email": "john.doe@example.com", "age": 35 }
You can parse this data into a SWIFT object as follows:
let jsonData = """ { "name": "John Doe",
"email": "john.doe@example.com",
"age": 35 } """.data(using: .utf8)
do {
let user = try JSONDecoder().decode(User.self, from: jsonData) print(user)
}
catch {
print(error)
}
Writing JSON in SWIFT
To write JSON data in SWIFT, you can use the built-in JSONEncoder
class. The JSONEncoder
class allows you to convert SWIFT objects into JSON data. To use the JSONEncoder
class, you simply need to create an instance of the class and pass a SWIFT object to it. The JSONEncoder
class will then convert the SWIFT object into JSON data that you can work with.
For example, if you have a SWIFT object that represents a user:
let user = User(name: "John Doe",
email: "john.doe@example.com",
age: 35)
You can convert this object into JSON data as follows:
do {
let jsonData = try JSONEncoder().encode(user)
let jsonString = String(data: jsonData, encoding: .utf8)
print(jsonString)
}
catch {
print(error)
}
Conclusion
Reading and writing JSON data is a common task in SWIFT programming, and the JSONDecoder
and JSONEncoder
classes make it easy to work with JSON data in SWIFT.
Cookbook – SWIFT for Beginners – Chapter 24: Reading & Writing JSON
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