How to loop through JSON with SwiftyJSON?

Question

I have a json that I could parse with SwiftyJSON :

if let title = json["items"][2]["title"].string {
     println("title : \(title)")
}

Works perfectly.

But I couldn't loop through it. I tried two methods, the first one is

// TUTO :
//If json is .Dictionary
for (key: String, subJson: JSON) in json {
    ...
}
// WHAT I DID :
for (key: "title", subJson: json["items"]) in json {
    ...
}

XCode didn't accept the for loop declaration.

The second method :

// TUTO :
if let appArray = json["feed"]["entry"].arrayValue {
     ...
}
// WHAT I DID :
if let tab = json["items"].arrayValue {
     ...
}

XCode didn't accept the if statement.

What am I doing wrong ?

score 79 · Accepted Answer · answered Feb 06 '15 at 15:28

79

If you want loop through json["items"] array, try:

for (key, subJson) in json["items"] {
    if let title = subJson["title"].string {
        println(title)
    }
}

As for the second method, .arrayValue returns non Optional array, you should use .array instead:

if let items = json["items"].array {
    for item in items {
        if let title = item["title"].string {
            println(title)
        }
    }
}

answered Feb 06 '15 at 15:28

rintaro

51,423
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when I try looping through my dictionary of [String: JSON] I get the error: '[String : JSON]?' does not have a member named 'Generator' – mattgabor Aug 18 '15 at 20:26
because it's optional – nikans Dec 05 '15 at 13:14
@rintaro I used your method and it works, but I'm just not sure if I'm being efficient or not. If you had multiple `items` to capture (ex. title, author, comment) would you simply repeat ` if let <> = item["<>"].string {}` for each of them? – Craig.Pearce Jan 22 '16 at 02:10
@Craig.Pearce Basically, yes. But if you mind "efficiency", IMO you should not use SwiftyJSON. see: [SwiftyJSON Performance Issues](http://stackoverflow.com/q/29252158/3804019) – rintaro Jan 22 '16 at 02:18
@rintaro - Very interesting. For my initial application, SwiftyJSON should be ok, but I will bookmark that SO conversation for future consideration. Thanks. – Craig.Pearce Jan 22 '16 at 02:24

score 11 · Answer 2 · answered Jul 09 '15 at 21:05

I Find it a bit strange explained myself, because actually using:

for (key: String, subJson: JSON) in json {
   //Do something you want
}

gives syntax errors (in Swift 2.0 atleast)

correct was:

for (key, subJson) in json {
//Do something you want
}

Where indeed key is a string and subJson is a JSON object.

However I like to do it a little bit different, here is an example:

//jsonResult from API request,JSON result from Alamofire
   if let jsonArray = jsonResult?.array
    {
        //it is an array, each array contains a dictionary
        for item in jsonArray
        {
            if let jsonDict = item.dictionary //jsonDict : [String : JSON]?
            {
                //loop through all objects in this jsonDictionary
                let postId = jsonDict!["postId"]!.intValue
                let text = jsonDict!["text"]!.stringValue
                //...etc. ...create post object..etc.
                if(post != nil)
                {
                    posts.append(post!)
                }
            }
        }
   }

The correct syntax is for (key, subJson):(String, JSON) in json — Emptyless, May 23 '16 at 21:56

score 8 · Answer 3 · edited Feb 08 '15 at 16:49

8

In the for loop, the type of key can't be of the type "title". Since "title" is a string, go for : key:String. And then Inside the Loop you can specifically use "title" when you need it. And also the type ofsubJson has to be JSON.

And Since a JSON file can be considered as a 2D array, the json["items'].arrayValue will return multiple objects. It is highly advisable to use : if let title = json["items"][2].arrayValue.

Have a look at : https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Types.html

edited Feb 08 '15 at 16:49

m0bi5

8,900
7
33
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answered Feb 06 '15 at 12:48

Dhruv Ramani

2,633
2
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Please tick that green label on the left if I helped. Thanks! – Dhruv Ramani Feb 06 '15 at 13:45

score 1 · Answer 4 · answered May 01 '15 at 14:03

1

Please check the README

//If json is .Dictionary
for (key: String, subJson: JSON) in json {
   //Do something you want
}

//If json is .Array
//The `index` is 0..<json.count's string value
for (index: String, subJson: JSON) in json {
    //Do something you want
}

answered May 01 '15 at 14:03

tangplin

147
4

1

He stated in the question that he checked the docs. Not very helpful imo. Sorry. – John Shelley Oct 19 '15 at 18:27
This helped me quite a bit. Thanks – derickito Aug 14 '17 at 04:07

2rahulsk · Answer 5 · 2019-01-23T01:44:15.473

0

you can iterate through the json by:

for (_,subJson):(String, JSON) in json {

   var title = subJson["items"]["2"]["title"].stringValue

   print(title)

}

have a look at the documentation of SwiftyJSON. https://github.com/SwiftyJSON/SwiftyJSON go through the Loop section of the documentation

edited Jan 23 '19 at 01:44

answered Jan 21 '19 at 01:52

2rahulsk

488
4
10

1

While this might answer the authors question, it lacks some explaining words and/or links to documentation. Raw code snippets are not very helpful without some phrases around them. You may also find [how to write a good answer](https://stackoverflow.com/help/how-to-answer) very helpful. Please [edit] your answer - [From Review](https://stackoverflow.com/review/low-quality-posts/21982654) – Nick Jan 21 '19 at 02:51

How to loop through JSON with SwiftyJSON?

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