JSON

JSON

Freddy defines an enumeration called JSON to encapsulate JSON data. Since JSON data is structured, and exclusive, an enumeration is a great mechanism for modeling this data.

Here is the definition for JSON:

public enum JSON {
    case array([JSON])
    case dictionary([String: JSON])
    case double(Double)
    case int(Int)
    case string(String)
    case bool(Bool)
    case null
}

The enumeration JSON provides a case for all of the data types that JSON data encapsulates. Each case, with the exception of .null, provides an associated value so that it can carry with it the anticipated data.

The cases for .array and .dictionary have more complex associated values that can themselves carry with them instances of JSON. After all, a JSON array may contain dictionaries as its elements.

In the parlance of Freddy, this would be a JSON instance set to the case .array whose associated value is [.dictionary]. The .dictionary would then have String keys and JSON values, which would typically be .double, .int, .string, or .bool.

JSONLiteralConvertible

In the file JSONLiteralConveritble.swift, Freddy provides a number of extensions wherein JSON conforms to several LiteralConvertible protocols. This allows for code like this:

let json = ["results": [ 
        ["name": "Matt Mathias", "age": 32], 
        ["name": "Drew Mathias", "age": 33] 
      ] 
    ] as JSON

or

let json: JSON = ["results": [ 
        ["name": "Matt Mathias", "age": 32], 
        ["name": "Drew Mathias", "age": 33] 
      ] 
    ]
// where json is: 
// JSON.dictionary([String: .array(.dictionary([String: .int(Int)]))])

Thus, json represents a simple example of some JSON payload you may receive from calling a web service.

You can also create JSON literals like so:

let jsonBool: JSON = false  // JSON.bool(false)
let jsonString: JSON = "Freddy!" // JSON.string("Freddy!")
let jsonInt: JSON = 13 // JSON.int(13)