How to parse Array of JSON to array in Swift

Question

I'm trying to parse JSON which is like below

[
  {
    "People": [
      "Jack",
      "Jones",
      "Rock",
      "Taylor",
      "Rob"
    ]
  },
  {
    "People": [
      "Rose",
      "John"

    ]
  },
  {
    "People": [
      "Ted"
    ]
  }
]

to an array which results in:

[ ["Jack", "Jones", "Rock", "Taylor", "Rob"] , ["Rose", "John"], ["Ted"] ]

which is array of arrays.

I tried with code below

if let path = Bundle.main.path(forResource: "People", ofType: "json") {
    let peoplesArray = try! JSONSerialization.jsonObject(
            with: Data(contentsOf: URL(fileURLWithPath: path)),
            options: JSONSerialization.ReadingOptions()
    ) as? [AnyObject]
    for people in peoplesArray! {
        print(people)
    }
}

when I print "people" I get o/p as

{
  People = (
    "Jack",
    "Jones",
    "Rock",
    "Taylor",
    "Rob"
  );
}
{
  People = (
    "Rose",
    "John"
  );
}
...

I'm confused how to parse when it has "People" repeated 3 times

Trying to display content in UITableView where my 1st cell has "Jack" .."Rob" and Second cell has "Rose" , "John" and third cell as "Ted"

PLease help me to understand how to achieve this

mokagio · Accepted Answer · 2018-01-30 09:29:11Z

17

You can do this in an elegant and type safe way leveraging Swift 4 Decodable

First define a type for your people array.

struct People {
  let names: [String]
}

Then make it Decodable, so that it can be initialised with a JSON.

extension People: Decodable {

  private enum Key: String, CodingKey {
    case names = "People"
  }

  init(from decoder: Decoder) throws {
    let container = try decoder.container(keyedBy: Key.self)

    self.names = try container.decode([String].self, forKey: .names)
  }
}

Now you can easily decode your JSON input

guard
  let url = Bundle.main.url(forResource: "People", withExtension: "json"),
  let data = try? Data(contentsOf: url)
else { /* Insert error handling here */ }

do {
  let people = try JSONDecoder().decode([People].self, from: data)
} catch {
  // I find it handy to keep track of why the decoding has failed. E.g.:
  print(error)
  // Insert error handling here
}

Finally to get get your linear array of names you can do

let names = people.flatMap { $0.names }
// => ["Jack", "Jones", "Rock", "Taylor", "Rob", "Rose", "John", "Ted"]

answered Jan 30, 2018 at 9:29

mokagio

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3 Comments

kiran Over a year ago

How to have it in swiftyJson! with out codables

mokagio Over a year ago

@kiran I don't know how to do it in SwiftyJSON, sorry. I would recommend investing in migrating to Decodable, though. That way, you'll get rid of a third-party dependency.

FontFamily Over a year ago

This is a great, clean answer. Good use of the do/catch loop to avoid using a crash operator (!).

Bista · Accepted Answer · 2017-02-07 05:03:31Z

 var peoplesArray:[Any] = [
    [
        "People": [
        "Jack",
        "Jones",
        "Rock",
        "Taylor",
        "Rob"
        ]
    ],
    [
        "People": [
        "Rose",
        "John"

        ]
    ],
    [
        "People": [
        "Ted"
        ]
    ]
  ]

 var finalArray:[Any] = []

 for peopleDict in peoplesArray {
    if let dict = peopleDict as? [String: Any], let peopleArray = dict["People"] as? [String] {
        finalArray.append(peopleArray)
    }
 }

 print(finalArray)

output:

[["Jack", "Jones", "Rock", "Taylor", "Rob"], ["Rose", "John"], ["Ted"]]

In your case, it will be:

if let path = Bundle.main.path(forResource: "People", ofType: "json") {
    let peoplesArray = try! JSONSerialization.jsonObject(with: Data(contentsOf: URL(fileURLWithPath: path)), options: JSONSerialization.ReadingOptions()) as? [Any]

    var finalArray:[Any] = []

    for peopleDict in peoplesArray {
        if let dict = peopleDict as? [String: Any], let peopleArray = dict["People"] as? [String] {
            finalArray.append(peopleArray)
        }
    }

    print(finalArray)
}

Olcay Ertaş · Accepted Answer · 2020-08-11 15:25:36Z

1

let assume that the json is the encoded data

var arrayOfData : [String] = []
dispatch_async(dispatch_get_main_queue(),{
    for data in json as! [Dictionary<String,AnyObject>]
    {
        let data1 = data["People"]

        arrayOfData.append(data1!)
    }
})

You can now use the arrayOfData. :D

edited Aug 11, 2020 at 15:25

Olcay Ertaş

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answered Feb 10, 2017 at 9:42

Gabriel M.

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Comments

Olcay Ertaş · Accepted Answer · 2020-08-11 15:26:19Z

1

what you have here is first an array of 3 objects. each object is a dictionary where the key is people and the value is an array of strings. when you're trying to do jsonserialization, you have to cast it down to the expected result. So you have first an array of objects, then you have a dictionary with String: Any, then you obtain an array of String

let peoplesArray = try! JSONSerialization.jsonObject(with: Data(contentsOf: URL(fileURLWithPath: path)), options: []) as? [AnyObject]
guard let peoplesObject = peoplesArray["people"] as? [[String:Any]] else { return }
for people in peoplesObject {
    print("\(people)")
}

edited Aug 11, 2020 at 15:26

Olcay Ertaş

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answered Feb 7, 2017 at 3:50

anckydocky

763 bronze badges

3 Comments

Ashh Over a year ago

i get nil in peoplesObject when im executing..my JSON is right but not sure why

anckydocky Over a year ago

do you have your json inside your app or you're getting it as a response from the web? you're probably getting nil because of the ! from try, but I am not sure

anckydocky Over a year ago

look, this is an example of how I managed to parse the JSON response from LastFM

Olcay Ertaş · Accepted Answer · 2020-08-11 15:27:51Z

I couldn't pasted it in a comment, it is too long or something

static func photosFromJSONObject(data: Data) -> photosResult {
    do {
        let jsonObject: Any =
                try JSONSerialization.jsonObject(with: data, options: [])

        print(jsonObject)

        guard let
              jsonDictionary = jsonObject as? [NSObject: Any] as NSDictionary?,
              let trackObject = jsonDictionary["track"] as? [String: Any],
              let album = trackObject["album"] as? [String: Any],
              let photosArray = album["image"] as? [[String: Any]]
                else {
            return .failure(lastFMError.invalidJSONData)
        }
    }
}

And the json was something like:

{
  artist: {
    name: Cher,
    track: {
        title: WhateverTitle,
        album: {
          title: AlbumWhatever,
          image: {
             small: "image.px",
             medium: "image.2px",
             large: "image.3px"}
       ....

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