How to initialize a struct from a json object

Question

HI i am new to swift any idea . How to initialize a struct from a json object . i could not figure out how can i do it .

{ "user": { "name": "cruskuaka", "email": "[e-mail]", "phoneNo":"018833455" }, "address": { "house": "100", "street": "B", "town": { "town_id": "1", "town_name": "Galway city center" }, "city": { "city_id": "10", "city_name": "Galway" }, "address_id":"200", "full_address":"100, B, Galway city center,Galway" }, "delivery_instruction": "no call", "delivery_method": "1" }

Here all struct :

struct Contact  {
    let user : User
    let address : Address
    let deliveryInstruction : String
    let deliveryMethod : String
    init(dictionary: [String: Any]) {
        self.deliveryInstruction = dictionary["delivery_instruction"] as? String ?? ""
        self.deliveryMethod = dictionary["delivery_method"] as? String ?? ""
        self.address = Address(dictionary: dictionary["address"] as? [String:Any] ?? [:])
        self.user =  User(dictionary: dictionary["address"] as? [String:Any] ?? [:])
    }
  }

---

struct User {
    let name : String
    let email : String
    let phoneNo : String
    init(dictionary : [String:Any] ) {
        self.name = dictionary["name"] as? String ?? ""
        self.email = dictionary["email"] as? String ?? ""
        self.phoneNo = dictionary["phoneNo"] as? String ?? ""
    }
}

---

struct Address  {
    let city : City
    let town : Town
    let addressId : String
    let fullAddress : String
    let house : String
    let street: String
    init(dictionary : [String:Any] ) {
        self.addressId = dictionary["address_id"] as? String ?? ""
        self.fullAddress = dictionary["full_address"] as? String ?? ""
        self.house = dictionary["house"] as? String ?? ""
        self.street = dictionary["street"] as? String ?? ""
        self.city = City(dictionary: dictionary["address"] as? [String:Any] ?? [:])
        self.town = Town(dictionary: dictionary["address"] as? [String:Any] ?? [:])  
    }
}

---

struct City {
    let cityId : String
    let cityName : String
    init(dictionary : [String:Any] ) {
        self.cityId = dictionary["city_id"] as? String ?? ""
        self.cityName = dictionary["city_name"] as? String ?? ""
    }
}

---

struct Town {
    let townId : String
    let townName : String
    init(dictionary : [String:Any]) {
        self.townId = dictionary["town_id"] as? String ?? ""
        self.townName = dictionary["town_name"] as? String ?? ""
    }
} 

Answer 1

You have more than one error in your code, but you are in the right path. You are using the wrong key when initializing your user, city and town structs. I have also created two more initializers so you can initialize your struct with a dictionary, the json string or just its data:

struct Contact: CustomStringConvertible  {
    let user: User
    let address: Address
    let deliveryInstruction: String
    let deliveryMethod: String
    // customize the description to your needs
    var description: String { return "\(user.name) \(deliveryInstruction) \(deliveryMethod)" }
    init(dictionary: [String: Any]) {
        self.deliveryInstruction = dictionary["delivery_instruction"] as? String ?? ""
        self.deliveryMethod = dictionary["delivery_method"] as? String ?? ""
        self.address = Address(dictionary: dictionary["address"] as? [String: Any] ?? [:])
        self.user =  User(dictionary: dictionary["user"] as? [String: Any] ?? [:])
    }
    init?(data: Data) {
        guard let json = (try? JSONSerialization.jsonObject(with: data)) as? [String: Any] else { return nil }
        self.init(dictionary: json)
    }
    init?(json: String) {
        self.init(data: Data(json.utf8))
    }

}

---

struct User: CustomStringConvertible {
    let name: String
    let email: String
    let phone: String
    let description: String
    init(dictionary: [String: Any]) {
        self.name = dictionary["name"] as? String ?? ""
        self.email = dictionary["email"] as? String ?? ""
        self.phone = dictionary["phoneNo"] as? String ?? ""
        self.description = "name: \(name) - email: \(email) - phone: \(phone)"
    }
}

---

struct Address: CustomStringConvertible  {
    let id: String
    let street: String
    let house: String
    let city: City
    let town: Town
    let description: String
    init(dictionary: [String: Any] ) {
        self.id = dictionary["address_id"] as? String ?? ""
        self.description = dictionary["full_address"] as? String ?? ""
        self.house = dictionary["house"] as? String ?? ""
        self.street = dictionary["street"] as? String ?? ""
        self.city = City(dictionary: dictionary["city"] as? [String: Any] ?? [:])
        self.town = Town(dictionary: dictionary["town"] as? [String: Any] ?? [:])
    }
}

---

struct City: CustomStringConvertible {
    let id: String
    let name: String
    // customize the description to your needs
    var description: String { return name }
    init(dictionary: [String: Any] ) {
        self.id = dictionary["city_id"] as? String ?? ""
        self.name = dictionary["city_name"] as? String ?? ""
    }

}

---

struct Town: CustomStringConvertible {
    let id: String
    let name: String
    // customize the description to your needs
    var description: String { return name }
    init(dictionary: [String: Any]) {
        self.id = dictionary["town_id"] as? String ?? ""
        self.name = dictionary["town_name"] as? String ?? ""
    }
}

Testing the initialization from JSON:

let json = "{\"user\": {\"name\": \"crst\",\"email\": \"[e-mail]\",\"phoneNo\":\"018833455\"},\"address\": {\"house\": \"100\",\"street\": \"B\",\"town\":{\"town_id\": \"1\",\"town_name\": \"Galway city center\"},\"city\":{\"city_id\": \"10\",\"city_name\": \"Galway\"},\"address_id\":\"200\", \"full_address\":\"100, B, Galway city center,Galway\" },\"delivery_instruction\": \"no call\",\"delivery_method\": \"1\" }"


let contact = Contact(json: json)   // crst no call 1

contact               // crst no call 1
contact?.user         // name: crst - email: [e-mail] - phone: [phone]
contact?.user.name    //  "crst"
contact?.user.email   //  "[e-mail]"
contact?.user.phone   //  "018833455"
contact?.address      //  100, B, Galway city center,Galway
contact?.address.id           //  200
contact?.address.street       //  B
contact?.address.town         // Galway city center
contact?.address.city         //  Galway
contact?.deliveryInstruction  // "no call"
contact?.deliveryMethod       //    1