Json returns null in swift

Question

I am trying to get value from a json file but it returns null.

Here is the code:

     Alamofire.request( jsonUrl).responseJSON { (responseData) -> Void in
        if((responseData.result.value) != nil) {


            let swiftyJsonVar = JSON(responseData.result.value!)["value"]
            print(swiftyJsonVar)
            let temp = swiftyJsonVar["value"]
            print(temp)
        }
    }

Here is the output from swiftyJsonVar:

[
  {
    "value" : "13.1",
    "quality" : "G",
    "date" : 1564772400000
  }
]

And the output from temp is null.

Why is temp null and not 13.1?

Use JSON(responseData.result.value!)[0]["value"]

Muhammed Gül
– Muhammed Gül

2019-08-03 20:02:21 +00:00
Commented Aug 3, 2019 at 20:02 — Muhammed Gül
– Muhammed Gül, Commented Aug 3, 2019 at 20:02

Mojtaba Hosseini · Accepted Answer · 2019-12-05 14:57:06Z

2

This will be an array: responseData.result.value

The array contains a dictionary with a key named value

So you should take first element of the array and then take the value of the value key like this:

JSON(responseData.result.value!)[0]["value"]

- A better way to work with a JSON:

Take a look at Codable. This is much better way to deal with json.

with Codable you first define your object:

struct MyDTO {
    let value: String,
    let quality: String,
    let date: Int // or any type you need
}

Then you decode it with a JSONDecoder:

let results = try! JSONDecoder().decode([MyDTO].self, from: responseData)

and lastly you can access your needed item like this:

results.first!.value

Remember to handle ! in a proper way.

edited Dec 5, 2019 at 14:57

answered Aug 3, 2019 at 20:06

Mojtaba Hosseini

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