How can I convert an array of objects that conform Codable protocol to an array of Dictionary?

Question

I have a struct like:

struct Demo: Codable {
    var foo: String
    var bar: String
    ...
}

And I have an array of demo:

let array = [Demo(foo: "a", bar: "b"), Demo(foo: "c", bar: "d")]

And I want to convert this array to a Dictionary [[String: Any]] with something like this:

let dictionary:[[String : Any]] = array.toDictionaryFromArrayOfCodable()

How can I get it?

Edit: My expected output is something like, and I want to use JSONEncoder:

[["foo": "a", "bar": "b"], ["foo": "c", "bar": "d"]]

try this -> let dict = try JSONDecoder().decode([String: Any].self, from: JSONEncoder().encode(array)) — vivekDas
– vivekDas, Commented Aug 3, 2018 at 9:02
@vivekDas using decode([String: Any] I have an error: "Type 'Any does not conform to protocol 'Decodable'. Changing it to decode([String: String], it compiles but I have an error: typeMismatch(Swift.Dictionary<Swift.String, Any>, Swift.DecodingError.Context(codingPath: [], debugDescription: "Expected to decode Dictionary<String, Any> but found an array instead.", underlyingError: nil)) — Diego Carrera
– Diego Carrera, Commented Aug 3, 2018 at 9:24

Diego Carrera · Accepted Answer · 2018-08-28 10:21:03Z

2

I found a solution using two extensions: - First to get a dictionary from an object - Second, to create an array of dictionaries with each elements of an array, using first extension:

Usage:

let dictionary = [Demo].asDictionaryFromArray()
print(dictionary)

output as expected: [["bar": b, "foo": a], ["bar": d, "foo": c]]

extension Encodable {

    var dictionaryFromObject: [String: Any]? {
        guard let data = try? JSONEncoder().encode(self) else { return nil }
        return (try? JSONSerialization.jsonObject(with: data, options: .allowFragments)).flatMap { $0 as? [String: Any] }
    }

}

extension Array where Element: Encodable {

    func asDictionaryFromArray() -> [[String: Any]] {
        var dict = [[String: Any]]()

        _ = self.map {
            if let objectDict = $0.dictionaryFromObject {
                dict.append(objectDict)
            }
        }

        return dict
    }

}

edited Aug 28, 2018 at 10:21

answered Aug 28, 2018 at 10:14

Diego Carrera

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