Parsing of JSON by Codable to array - json

Question

I have following JSON:
[
{
"id": 1,
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [
37.5741167,
55.7636592
]
},
"properties": {
"hintContent": "переулок Волков, 13с1",
"balloonContentHeader": "переулок Волков, 13с1"
}
]
I am trying to use JSONDecoder:
struct Point : Codable {
let id: Int
let type: String
let properties: Properties
}
struct Properties : Codable {
let hintContent: String
let balloonContentHeader: String
}
struct Points : Codable {
var data : [Point]
}
func parse(fileName: String) {
let url = Bundle.main.url(forResource: fileName, withExtension: "json")
let data = try? Data(contentsOf: url!)
if let jsonPoints = try? JSONDecoder().decode([Point].self, from: data!) {
print(jsonPoints)
}
}
What is wrong?

Answer 1

Make sure your JSON is valid -- this one has a missing }.
Paste your (valid) JSON into app.quicktype.io to generate models ie. make sure that your models match the JSON. In the event that your JSON isn't valid, that site will warn you about it as well.
Always use do/try/catch and not try? so that you can get meaningful errors when JSON decoding fails.
let data = """
[
{
"id": 1,
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [
37.5741167,
55.7636592
]
},
"properties": {
"hintContent": "t",
"balloonContentHeader": "t"
}
}
]
""".data(using: .utf8)
struct Point: Codable {
let id: Int
let type: String
let geometry: Geometry
let properties: Properties
}
// MARK: - Geometry
struct Geometry: Codable {
let type: String
let coordinates: [Double]
}
// MARK: - Properties
struct Properties: Codable {
let hintContent, balloonContentHeader: String
}
func parse(fileName: String) {
do {
let jsonPoints = try JSONDecoder().decode([Point].self, from: data!)
print(jsonPoints)
} catch {
print(error)
}
}
Without the adjusted JSON, your original code would generate this error in the catch block:
The given data was not valid JSON....Badly formed object around character 224.