How to parse a JSON file in swift?

Question

I have a JSON file, want to parse and use list of objects in table view. Can any one share the code to parse JSON file in swift.

Accepted Answer

This answer was last revised for Swift 5.3 and iOS 14.4 SDK.

Given some already obtained JSON data, you can use `JSONDecoder` to decode it into your `Decodable` model (or a collection of models).

```
let data: Data = /* obtain your JSON data */
let model = try JSONDecoder().decode(Model.self, from: data)
```

Such model must conform to the `Decodable` protocol and contain correct mapping between properties and JSON dictionary keys. As an example, consider the following JSON array containing search results of cities beginning with "Wa".

```
[
    {
        "id": 123,
        "city": "Washington",
        "region": "D.C.",
        "country": "United States"
    },
    {
        "id": 456,
        "city": "Warsaw",
        "region": "Mazowieckie",
        "country": "Poland"
    },
    ...
]
```

For that, you need to create a model that contains the correct properties of correct types. If you're using a web API, its documentation will be of great help here.

```
struct SearchResult: Decodable {
    let id: Int
    let city: String
    let region: String
    let country: String
}
```

Then decode the data with `JSONDecoder`:

```
let results = try JSONDecoder().decode([SearchResult].self, from: data)
```

Given a new array of decoded search results, call one of `UITableView`'s functions to reload its data. Note that the `decode` function can throw an error which you must somehow handle.

To learn more about decoding custom types in Swift and more advanced usage of the `Codable` APIs, I recommend checking out this documentation article.

How to parse a JSON file in swift?

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