Xcode swift parse json codable

Question

I'm trying to understand the best way to parse a json file with the Codable.

This is the json structure.

{
    "type": "Feature",
    "features": [
        {
            "type": "Feature",
            "geometry": {
                "coordinates": [
                    [10.23, 48.32],
                    [10.24, 48.33],
                    [10.25, 48.34],
                    [10.26, 48.35],
                    [10.27, 48.36]
                ]
            }
        }
    ]
}

What I need is the list of coordinates. I tried to implement this structures but I have some problems.

struct Root: Codable {
    let features: [Features]
}

struct Features: Codable {
    let geometry: [Coordinates]
}

struct Geometry: Codable {
    let coordinates: [Coordinates]
}

struct Coordinates: Codable {
    let latitude: [Double]
    let longitude: [Double]
}

Then I call the JSONDecoder function like this

let coordinates = try JSONDecoder().decode(Root.self, from: data)

I think that the error is that the coordinates are in a sublist. I'm new in this world so sorry if the question is a little bit dummy but I haven't find an explanation by my self.

What exactly is the error?

koen
– koen

2022-04-02 11:14:30 +00:00
Commented Apr 2, 2022 at 11:14 — koen
– koen, Commented Apr 2, 2022 at 11:14
This is GeoJSON. Use MKGeoJSONDecoder

vadian
– vadian

2022-04-02 14:16:01 +00:00
Commented Apr 2, 2022 at 14:16 — vadian
– vadian, Commented Apr 2, 2022 at 14:16

workingdog support Ukraine · Accepted Answer · 2022-04-02 11:38:30Z

3

you were almost there. Try this:

struct Root: Codable {
    let features: [Feature]
}

struct Feature: Codable {
    let geometry: Geometry
}

struct Geometry: Codable {
    let coordinates: [[Double]]
}

and:

let root = try JSONDecoder().decode(Root.self, from: data)

and:

for feature in root.features {
    let coords = feature.geometry.coordinates
    print("\(coords)")
}

PS: your data seems to be GeoJSON. Read-up on Swift GeoJSON and how to decode it.

edited Apr 2, 2022 at 11:38

answered Apr 2, 2022 at 11:17

workingdog support Ukraine

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