Swift 3 - save json using struct model with null value - ios

Question

I am working on consuming the restful web service which returns the data in JSON format. This is the Sample data :
[
{
"name": "Mark E",
"categories": "process",
"id": 1,
"checkedOut": null,
"checkedOutBy": null
},
{
"name": "John",
"categories": null,
"id": 2,
"checkedOut": null,
"checkedOutBy": null
}
]
I am parsing this json using this code. Also I created struct model for this.
let task = session.dataTask(with: url) { (data, response, error) in
var myModel = [MyModel]()
if let HTTPResponse = response as? HTTPURLResponse {
let status = HTTPResponse.statusCode
if(status == 200) {
guard let data = data else {
print("No Data!!")
return completion(false, myModel)
}
guard let json = try! JSONSerialization.jsonObject(with: data, options: []) as? NSArray else {
print("Not an array")
return completion(false, myModel)
}
for jsondata in json {
guard let newdata = MyModel(json: jsondata) else {
continue
}
myModel.append(newdata)
}
completion(true,myModel)
}else {
completion(false,myModel)
}
}
}
task.resume()
And this is my data model struct
struct MyModel {
var name : String
var categories : String
var id : Int
var checkedOut : String
var checkedOutBy : String
init?(json:Any) {
guard let myModel = json as? NSDictionary else {
return nil
}
guard let name = myModel["name"] as? String,
let id = myModel["id"] as? Int else {
return nil
}
self.name = author
self.id = id
// This is how I am handling the null values.
if let categories = myModel["categories"] as? String {
self.categories = categories
} else {
self.categories = ""
}
if let lastCheckedOut = myModel["lastCheckedOut"] as? String {
self.lastCheckedOut = lastCheckedOut
} else {
self.lastCheckedOut = ""
}
if let lastCheckedOutBy = myModel["lastCheckedOutBy"] as? String {
self.lastCheckedOutBy = lastCheckedOutBy
}else {
self.lastCheckedOutBy = ""
}
}
}
Here in struct MyModel, I am using if let for checking null values. Could anyone please suggest me this is the right way to check each variable for null? Is there any other way to do this?
If I check for null value using guard, its not adding any object into array.
If the value is null then it simply assign empty char "" to that variable and it will add into MyModel array of objects.

Answer 1

The usual way to check for a specific type and assign something else on failure is the nil coalescing operator:
self.lastCheckedOut = myModel["lastCheckedOut"] as? String ?? ""
Side-note: Consider that JSON null is deserialized to NSNull rather than to nil

Answer 2

I would advise on a couple of approaches:
Setting MyModel struct properties as optionals. In this way, you don't need to use if let or guard statements.
I can recommend ObjectMapper, a Swift 3 pods which maps JSON very efficiently. For example:
Instead of assigning:
If let _value = dictionary["value"] as? String { self.value = _value
}
You will use
self.value = map["value"]
ObjectMapper
Wrote this on my phone, untested ;-)...