How parse json recursively using codable with swift - swift

Question

I am trying to defining a decoding class model to decode this kind of json file:
Here a short extraction to understand the problem, in reality it is more nested.
{
"Title" : "Root",
"Subtitle" : "RootTree",
"Launch" : [
{
"DisplayName" : "Clients",
"Launch" : [
{
"DisplayName" : "Clients Details",
"Launch" : [
{
"DisplayName" : "Item1",
"URI" : "/rest/..."
},
{
"DisplayName" : "Item2",
"URI" : "/rest/..."
},
{
"DisplayName" : "Item3",
"URI" : "/rest/..."
}
]
}
]
}
]
}
Here my structure, I used a class because of the recursive usage:
final class Url: Codable {
let name : String
let uri: String?
let launch: [LaunchStructure]?
enum CodingKeys: String, CodingKey {
case name = "DisplayName"
case uri = "URI"
case launch = "Launch"
}
}
final class LaunchStructure: Codable {
let launch: [Url]
enum CodingKeys: String, CodingKey {
case launch = "Launch"
}
}
In the Title and Subtitle I am not interested, therefore I have excluded it from the class. I would like to get the Displayname and the uri from the items. As I said, the structure is more nested, but always the same structure. Is it possible to read the elements using a recursive way.
I am to decode it in this manner:
...
let result = Result { try JSONDecoder().decode(LaunchStructure.self, from: data) }
Thank you, best regards
Arnold

Answer 1

You don't need two types here at all, just one will do:
struct Item: Codable {
let name : String? // not all entries in your example has it, so it's optional
let uri: String?
let launch: [Item]? // same here, all leaf items doesn't have it
enum CodingKeys: String, CodingKey {
case name = "DisplayName"
case uri = "URI"
case launch = "Launch"
}
}