README.md

YHJSONGenerator

A library to generate json object from almost any instance of class or struct.

API

This library extends JSONSerialization with 3 methods:

 /// This method generates json object from any instance of a class or a struct, or a dictionary of valid item. **Note, This method only accept a instance of a class or a struct.**
    ///
    /// Define: A valid item is an object whose properties are all objects that conforms to JSONCompatible.
    /// - Parameter any: Any instance of a class or a struct
    /// - Returns: A json object whose root is a dictionary. If the parameter passed in is not a a instance of a class or struct, this method returns nil
    public static func jsonDictionaryObject(with any: Any) -> [String : Any]?

    /// This method generates json object from any array(or set) of instances. **Note, This method only accept a collection of valid items.**
    ///
    /// Define: A valid item is an object whose properties are all objects that conforms to JSONCompatible.
    ///
    /// - Parameter any: A collection of valid items.
    /// - Returns: A json object whose root is an array.
    public static func jsonArrayObject(with any: Any) -> [Any]?

    /// This method combines the `jsonDictionaryObject(with any: Any) -> [String: Any]?` and `jsonArrayObject(with any: Any) -> [Any]?`. In other words, it only accept a instance of a class or struct or a collection of valid items.
    ///
    /// - Parameters:
    ///   - any: Any instace
    ///   - opt: The options to write jsonObject
    /// - Returns: Data generated from JSON Object
    public static func jsonData(with any: Any, options opt: JSONSerialization.WritingOptions = default) throws -> Data

For example:

struct Restaurant {
    enum Meal: String {
        case breakfast, lunch, dinner
    }
    
    let name: String
    let location: (latitude: Double, longitude: Double)
    let meals: Set<Meal>
}

let restaurant = Restaurant(name: "Swift Dinner", location: (latitude: 123.456, longitude: 789.123), meals: [.breakfast, .lunch])

let restaurantJSON = JSONSerialization.jsonDictionaryObject(with: restaurant)
//print:
/*
  {
  "name" : "Swift Dinner",
  "location" : [
    123.456,
    789.123
  ],
  "meals" : [
    "breakfast",
    "lunch"
  ]
}
*/

let restaurants = [restaurant, restaurant, restaurant]
let restaurantsJSON = JSONSerialization.jsonArrayObject(with: restaurants)
//print:
/*
[
  {
    "name" : "Swift Dinner",
    "location" : [
      123.456,
      789.123
    ],
    "meals" : [
      "breakfast",
      "lunch"
    ]
  },
  {
    "name" : "Swift Dinner",
    "location" : [
      123.456,
      789.123
    ],
    "meals" : [
      "breakfast",
      "lunch"
    ]
  },
  {
    "name" : "Swift Dinner",
    "location" : [
      123.456,
      789.123
    ],
    "meals" : [
      "breakfast",
      "lunch"
    ]
  }
]
*/

These methods could convert any struct or class objects to JSON objects, as long as all the properties conforms to protol JSONCompatible. Here is a list of types conforms to JSONCompatible by default:

• ObjCBool

• Bool

• CGFloat

• String

• NSString

• Int

• Int8

• Int16

• Int32

• Int64

• UInt

• UInt8

• UInt16

• UInt32

• UInt64

• Float// aka. Float32

• Double// aka. Float64

• NSNull

• NSNumber

If your model contains properties that are not supported by JSON, you just need to make that type conform to JSONConvertible. You need to implement only one function toJSON() whitch returns a JSONCompatible type.

For example: If your model contains UIImage...

extension UIImage: JSONConvertible {
    public func toJSON() -> JSONCompatible {
        return UIImagePNGRepresentation(self)?.base64EncodedString() ?? ""
    }
}

struct Album {
    let name = "My album"
    var photo: UIImage = #imageLiteral(resourceName: "photo.jpg")
}


let album = Album()
let albumJSON = JSONSerialization.jsonDictionaryObject(with: album)

More examples:

extension URL: JSONConvertible {
    public func toJSON() -> JSONCompatible {
        return absoluteString
    }
}
extension Date: JSONConvertible {
    public func toJSON() -> JSONCompatible {
        return self.timeIntervalSince1970 * 1000
    }
}

To try the library yourself, you can download the repository and open Demo.playground.

How to install

To use this library, just drag and drop YHJSONGenerator to your project.

JSON to Swift?

If you are interested in converting JSON to Swift model. Please refer to my another repository: SwiftJSONSolution.