Convert Array<CustomObject> to JSON - ios

Question

I hava a problem I can't convert array to JSON in SWIFT 3.0 . I am using ObjectMapper
My object
class OrderItem: Mappable {
required init?(map: Map) {
}
init() {
}
var oi_id: Int? = 0
var quantity: Double? = 0.0
var discount: Double = 0.0
var sku: Int? = 0
var orderId: Int? = 0
var Product: Product?
var isAdd: Bool = false
var isMissing: Bool!
func mapping(map: Map) {
oi_id <- map["oi_id"]
quantity <- map["quantity"]
discount <- map["discount"]
orderId <- map["orderId"]
Product <- map["Product"]
isAdd <- map["isAdd"]
isMissing <- map["isMissing"]
}}
Convert/ generating the result JSON :
var jsonArrayOrderItem = arrayOrderItem.toJSON()
Result JSON after convert . JSON is wrong :(
[["oi_id": 0, "isAdd": false, "quantity": 1.0, "Product": ["isHot": false, "discount": 50.0, "description": "description", "Acronym": "kg", "priceWithDiscount": 0.62, "bigValue": 1.0, "sku": 14, "Name": "Green Apples", "Price": 1.23, "IsFavorite": true, "smallValue": 0.20000000000000001, "Category": ["bigImageUrl": "https://i.imgur.com/7R3sFnP.png", "ImageUrl": "https://i.imgur.com/NJP4CuA.png", "cat_id": 11, "Name": "Fruits & vegetables", "Products": []], "MeasurementUnitId": 0, "ImageUrl": "https://s22.postimg.org/5992ux3j5/Green_apples.jpg", "CategoryId": 11, "Brand": ["brand_id": 8, "name": "Arbella", "imageUrl": "http://i.imgur.com/xx5ZAgL.jpg", "Products": []]], "orderId": 0, "discount": 0.0], ["oi_id": 0, "isAdd": false, "quantity": 1.0, "Product": ["isHot": false, "discount": 50.0, "description": "description", "Acronym": "kg", "priceWithDiscount": 0.62, "bigValue": 1.0, "sku": 17, "Name": "Mango", "Price": 1.23, "IsFavorite": true, "smallValue": 0.20000000000000001, "Category": ["bigImageUrl": "https://i.imgur.com/7R3sFnP.png", "ImageUrl": "https://i.imgur.com/NJP4CuA.png", "cat_id": 11, "Name": "Fruits & vegetables", "Products": []], "MeasurementUnitId": 0, "ImageUrl": "https://s22.postimg.org/4om6zb2zl/Mango.jpg", "CategoryId": 11, "Brand": ["brand_id": 8, "name": "Arbella", "imageUrl": "http://i.imgur.com/xx5ZAgL.jpg", "Products": []]], "orderId": 0, "discount": 0.0]]

Answer 1

try for Swift 4.0 - It has inbuilt JSONDecoder.