Codable protocol for JSON parsing in iOS Swift - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the Codable protocol in Swift?

The Codable protocol allows Swift types to be easily encoded to and decoded from external representations like JSON, making data parsing and serialization simple.

beginner

Which two protocols does Codable combine?

Codable combines Encodable (for encoding data) and Decodable (for decoding data).

beginner

How do you decode JSON data into a Swift struct that conforms to Codable?

Use <code>JSONDecoder</code> to decode JSON data into the struct. For example: <br><code>let decoded = try JSONDecoder().decode(MyStruct.self, from: jsonData)</code>

beginner

What must you do to a Swift struct to make it parse JSON automatically?

Make the struct conform to Codable and ensure all its properties are also Codable types.

intermediate

How can you handle JSON keys that don't match your Swift property names?

Implement a CodingKeys enum inside your struct to map JSON keys to your property names.

What does the Codable protocol help you do in Swift?

A Handle network connections

B Create user interfaces

C Manage memory manually

D Parse and generate JSON data easily

Codable is designed to help encode and decode data formats like JSON, not UI or networking.

Which class is used to decode JSON data into Swift types?

A JSONEncoder

B JSONDecoder

C DataDecoder

D JSONParser

JSONDecoder decodes JSON data into Swift types conforming to Decodable.

If your JSON key is user_name but your Swift property is userName, how do you handle this mismatch?

A Use a <code>CodingKeys</code> enum to map keys

B Rename the property to <code>user_name</code>

C Change the JSON key to <code>userName</code>

D You cannot handle this mismatch

The CodingKeys enum lets you map JSON keys to different property names.

What must all properties of a Codable struct be?

A Also conform to <code>Codable</code>

B Private

C Strings only

D Optional

All properties must be Codable to be encoded or decoded automatically.

Which protocol is NOT part of Codable?

A Encodable

B Decodable

C Serializable

D None of the above

Serializable is not a Swift protocol; Codable combines Encodable and Decodable.

Explain how to use the Codable protocol to parse JSON data into a Swift struct.

Think about the steps from defining the struct to decoding JSON.

Describe how you would handle a JSON key that does not match your Swift property name when using Codable.

Focus on the enum inside the struct.