Error while trying to phrase JSON with Swift

Question

I'm trying to receive data from a JSON link in Swift Playground on Mac, I've struct all the data, but I'm having issue trying to decode all of the data, receiving the error: "Referencing instance method 'decode(_:from:)' on 'Array' requires that 'Bicimia' conform to 'Decodable'"

I've already tries to add the Codable/Decodable option, and tried to change the URLSession respectively, but nothing has changed.

struct Bicimia {

    let network: Network

}


struct Network {

    let company: [String]
    let href, id: String
    let location: Location
    let name: String
    let stations: [Station]

}

struct Location {

    let city, country: String
    let latitude, longitude: Double

}

struct Station {

    let emptySlots: Int
    let extra: Extra
    let freeBikes: Int
    let id: String
    let latitude, longitude: Double
    let name, timestamp: String

}

struct Extra {

    let extraDescription: String
    let status: Status

}

enum Status {

    case online
}


let url = "https://api.citybik.es/v2/networks/bicimia"
let urlOBJ = URL(string: url)

URLSession.shared.dataTask(with: urlOBJ!) {(data, response, error) in


    do {
        let res = try JSONDecoder().decode([Bicimia].self, from: data!)
        print(res)
    }
    catch {
        print(error)
    }
}.resume()

Do what the error suggests: Add conformance to `Decodable` to all structs. `struct ... : Decodable {` — vadian, Oct 05 '19 at 19:52
I've already tried adding :Decodable to all struct, but I receive an error that says: "Type 'Extra' does not conform to protocol 'Decodable'" — Giovanni Filippini, Oct 05 '19 at 19:57
Looking at the JSON `Status` has cases `online` and `offline` so change the enum to `enum Status : String, Decodable { case online, offline }` — vadian, Oct 05 '19 at 20:04

score 1 · Accepted Answer · answered Oct 05 '19 at 20:04

1

To be Decodable all properties should be Decodable down the chain:

struct Bicimia: Decodable {
    let network: Network // should be decodable
}

struct Network: Decodable {
    let company: [String]
    let href, id: String
    let location: Location // should be decodable
    let name: String
    let stations: [Station] // should be decodable
}

struct Location: Decodable {
    let city, country: String
    let latitude, longitude: Double
}

struct Station: Decodable {
    let emptySlots: Int
    let extra: Extra // should be decodable
    let freeBikes: Int
    let id: String
    let latitude, longitude: Double
    let name, timestamp: String
}

struct Extra: Decodable {
    let extraDescription: String
    let status: Status // should be decodable
}

enum Status: String, Decodable {
    case online
}

Note that enums can not be Decodable alone, because they should know what is the raw value, or you should manually decode them in decode function.

answered Oct 05 '19 at 20:04

Mojtaba Hosseini

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That worked without problem, but now in the terminal I receive an error saying: "typeMismatch(Swift.Array, Swift.DecodingError.Context(codingPath: [], debugDescription: "Expected to decode Array but found a dictionary instead.", underlyingError: nil))" – Giovanni Filippini Oct 05 '19 at 20:07
1

use `let res = try JSONDecoder().decode(Bicimia.self, from: data!)` instead of [Bicimia.self]... – Stephan Schlecht Oct 05 '19 at 20:09
That is another issue, but you should decode as @StephanSchlecht mentioned. Please do not ask another question in the comment. Except, feel free [to ask a new one](https://stackoverflow.com/questions/ask) if you need to. And don't forget to **mark as answer** if this was the answer to the original question as you said. – Mojtaba Hosseini Oct 05 '19 at 20:22

Error while trying to phrase JSON with Swift

1 Answers1