Swift 3 - How to convert an array of structs that contain structs to JSON?

Question

I have an array of Field structs that I want to convert to a JSON string.

Field is defined as:

struct Field{

    var name: St         


        

Answer 1

struct LatLng {
    let latitude: Double
    let longitude: Double

    func getJSON() -> NSMutableDictionary {
        let dict = NSMutableDictionary()
        dict.setValue(latitude, forKey: "latitude")
        dict.setValue(longitude, forKey: "longitude")
        return dict
    }
}

struct Field {
    var name: String
    var center: LatLng
    var perimeter: [LatLng]

    func getJSON() -> NSMutableDictionary {
        let values = NSMutableDictionary()

        var perimeterArray = Array()
        for item in perimeter {
            perimeterArray.append(item.getJSON())
        }

        values.setValue(name, forKey: "name")
        values.setValue(center.getJSON(), forKey: "center")
        values.setValue(perimeterArray, forKey: "perimeter")

        return values

    }
}

let peri = [LatLng(latitude: 10.0, longitude: 10.0), LatLng(latitude: 20.0, longitude: 20.0)]
let center = LatLng(latitude: 15.0, longitude: 15.0)

let field = Field(name: "test", center: center, perimeter: peri)

let json = try NSJSONSerialization.dataWithJSONObject(field.getJSON(), options: .PrettyPrinted)
let jsonString = NSString(data: json, encoding: NSUTF8StringEncoding)
print(jsonString)

//PRINTS THE FOLLOWING OUTPUT
Optional({
    "name" : "test",
    "center" : {
        "longitude" : 15,
        "latitude" : 15
    },
    "perimeter" : [{
        "longitude" : 10,
        "latitude" : 10
    },
    {
        "longitude" : 20,
        "latitude" : 20
    }]
})

UPDATE

In order to serialise an array of Field objects, you can do something like this.

let field1 = Field(name: "value1", center: center, perimeter: peri)
let field2 = Field(name: "value2", center: center, perimeter: peri)
let field3 = Field(name: "value3", center: center, perimeter: peri)

let fieldArray = [field1.getJSON(), field2.getJSON(), field3.getJSON()]

let json = try NSJSONSerialization.dataWithJSONObject(fieldArray, options: .PrettyPrinted)
let jsonString = NSString(data: json, encoding: NSUTF8StringEncoding)

Please note that this is just a quick solution, not the best one. This is just to give you an idea of how it will go. I'm sure you'll be able to improve on it.