Parsing JSON in Swift - json

Question

I want to parse JSON object that receive from server. there is my code for parsing JSON and create object.
class Transaction {
var id: String!
var amount: String!
var balance: String!
var detail: String!
var serial: String!
var time : String!
var type: String!
init(id: String, amount: String, balance: String, detail:String, serial: String, time: String, type: String ) {
self.id = id
self.amount = amount
self.balance = balance
self.detail = detail
self.serial = serial
self.time = time
self.type = type
}
func CreateTransactionObject(json: [String:Any]) -> Transaction? {
guard let id = json["id"] as? String,
let amount = json["amount"] as? String,
let balance = json["balance"] as? String,
let detail = json["detail"] as? String,
let serial = json["serial"] as? String,
let time = json["time"] as? String,
let type = json["type"] as? String
else {
return nil
}
let object = Transaction(id: id, amount: amount, balance: balance, detail: detail, serial: serial, time: time, type: type)
return object
}
this work fine when guard statement don't return nil.
for example when one of the parameters is null guard statement return nil and object can't create.
how can parse JSON that if any object don't receive from server or get null ?

Answer 1

I recommend to use a dedicated init method.
Declare the properties in two ways:
If an empty string or 0 can represent no value declare the property as non-optional and use the nil coalescing operator (like the first 5 properties).
If no value must be handled separately declare the property as standard optional (like time and type)
class Transaction {
var id: String
var amount: String
var balance: Int
var detail: String
let serial: String
var time : String?
var type: String?
init(json: [String:Any]) {
self.id = json["id"] as? String ?? ""
self.amount = json["amount"] as? String ?? ""
self.balance = json["balance"] as? Int ?? 0
self.detail = json["detail"] as? String ?? ""
self.serial = json["serial"] as? String ?? ""
self.time = json["time"] as? String
self.type = json["type"] as? String
}
}
It's also a good habit to declare properties which are not going to change their value as constants with let (like serial). The initialization works the same way.

Answer 2

If the object is still usable if one of its properties is nil, declare the properties nil and use if let statements for optional unwrapping instead of the guard let. This way, the properties that don't exist will be initialized to nil, instead of the whole object being initialized to nil. This way you don't even need a designated initializer.
class Transaction {
var id: String?
var amount: String?
var balance: String?
var detail: String?
var serial: String?
var time : String?
var type: String?
func CreateTransactionObject(json: [String:Any]) -> Transaction {
let transaction = Transaction()
transaction.id = json["id"] as? String
transaction.amount = json["amount"] as? String
transaction.balance = json["balance"] as? String
transaction.detail = json["detail"] as? String
transaction.serial = json["serial"] as? String
transaction.time = json["time"] as? String
transaction.type = json["type"] as? String
return transaction
}
}