Swift 4 + Alamofire: parse array of custom struct

Question

My API returns the following JSON (an array of [CustomClass]):

[{
        "name": "Name A",
        "startingDate": "2018-01-01",
        "duration": 4
    },
    {
        "name": "Name B",
        "startingDate": "2018-01-01",
        "duration": 4
    }
]

I'm using Alamofire to make the request and then parsing the JSON:

static func test(parametersGet:Parameters, completion: @escaping ([CustomStruct]?, Error?) -> Void ) {
        Alamofire.request(API.test, parameters: parametersGet).validate().responseJSON { response in
            switch response.result {
            case .success:
                if let json = response.result.value {
                    let workoutCards = json as! [CustomStruct]
                    completion(workoutCards, nil)
                }
            case .failure(let error):
                completion(nil, error)
            }
        }
    }

CustomStruct it's simply a Codable struct with those keys.

I get the following error: "Could not cast value of type '__NSDictionaryI' to 'Project.CustomStruct'". How can I parse the JSON?

Possible duplicate of Parsing JSON Lines with Alamofire/Codable — David Pasztor
– David Pasztor, Commented Jun 18, 2018 at 16:30

Krishna Kumar Thakur · Accepted Answer · 2018-06-18 19:40:26Z

3

In Your case you will need to decode your jsonData to [CustomStruct] using JSONDecoder

  Alamofire.request(API.test, parameters: parametersGet).validate().responseJSON { response in
            switch response.result {
            case .success:
                if let jsonData = response.data {
                    let jsonDecoder = JSONDecoder()
                    do {
                        let workoutCards = try jsonDecoder.decode([CustomStruct].self, from: jsonData)
                        completion(workoutCards, nil)
                    }catch let error{
                        print(error.localizedDescription)
                        completion(nil, error)
                    }
                }
            case .failure(let error):
                completion(nil, error)
            }
        }

edited Jun 18, 2018 at 19:40

answered Jun 18, 2018 at 19:34

Krishna Kumar Thakur

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Comments

ironRoei · Accepted Answer · 2018-11-20 11:04:24Z

0

You can build a struct like so:

    struct Item {
        var name: String
        var startingDate: String
        var duration: String
    }

Then parse the data from the result:

                let jsonDecoder = JSONDecoder()
                do {
                    let workoutCards = try jsonDecoder.decode([Item].self, from: data)
                    completion(workoutCards, nil)
                }catch let error{
                    print(error.localizedDescription)
                    completion(nil, error)
                }
            }
        case .failure(let error):
            completion(nil, error)
        }

answered Nov 20, 2018 at 11:04

ironRoei

2,22929 silver badges49 bronze badges

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