Looping through a multidimensional array in swift

Using Swift
1

I am fairly new to swift and got some issues with looping through an array i got from a json file. So i can obtain the individual keys just fine but the amount of items inside my array differs so i need to loop through the content.

Imagine this being my JSON response:

{
"todo": [
{
"id": "31",
"title": "Loftdeur",
"done": "0"
},
{
"id": "32",
"title": "test",
"done": "0"
}, {
"id": "36",
"title": "test",
"done": "0"
}
]
}

My struct

struct Todolist: Codable {
let todo: [Todo]
}

struct Todo: Codable {
let id, title, done: String
}

I decode it with the code below:

do {

                let decoder = JSONDecoder()
                let response = try decoder.decode(Todolist.self, from: data!)
                print(response.todo[1].title) //Output - EMT
                
                let size = response.todo.count
                print(size)
                
                for(index, list) in response.todo.enumerated()
                {

                 print(list)
        }
   }

I can print an individual key:

print(response.todo[1].title)

when i print(list) inside my first for loop i get:

Todo(id: "31", title: "Loftdeur", done: "0")
Todo(id: "32", title: "test", done: "0")
Todo(id: "33", title: "test", done: "0")

I thought adding another for loop would do the trick but then i get an error:

   for title in list
        {
        print("item: \(title)")
         }

Type 'Todo' does not conform to protocol 'Sequence'

How can i loop through this array and grab each individual key of the array?

2

You cannot, because this is not an array.

Allow me to reproduce your two structure definitions again, reformatting Todo to make its definition a bit clearer:

struct Todolist: Codable {
    let todo: [Todo]
}

struct Todo: Codable {
    let id: String
    let title: String
    let done: String
}

When you decode your JSON as Todolist you get back a single Todolist object containing one array of Todo.

Your for (index, list) in response.todo.enumerated() line therefore produces two variables: index, of type Int, and list, of type Todo. The key here is that Todo is not an array, and does not contain an array. It's an object with 3 properties, each one a String.

So to get the elements, you do this:

for (index, list) in response.todo.enumerated() {
    print(list.id)
    print(list.title)
    print(list.done)
}
4 Likes
3

works likes a charm thanks!