Swift and accessing nested JSON collections

Question

I am accessing a CMS with a pre-baked JSON output and it uses the following data structure. I am struggling to get down into the nested collections to get the version or loop through the categories.

{
    results: [
        {
            pageData: {
                info: {
                    version: "1"
                },
                categories: [
                    {
                        name: "Cat 1"
                    },
                    {
                        name: "Cat 2"
                    }
                ]
            }
        }
    ]
}

Here is the code I was attempting to use. Any help is appreciated!

guard let json = json, let results = json["results"], let pageData = results["pageData"], let info = pageData["info"] as? [String:Int], let version = info["version"], 
    let categories = Category.getCategories(json: json) else {
    self.completionParse(RequestResult.errorParsing, self.categoriesResult)
    return
}

Your code indicates you understand how to dig into a dictionary to get the desired data. What issue are you having trying to obtain the slightly different data? — rmaddy
– rmaddy, Commented Feb 23, 2017 at 4:50
@rmaddy If I remove results and pageData collections and bring the info and categories collection to the top level the code above works. If I continue the let sequencing, and try and start at results and walk down it errors out and doesn't seem to work. Trying to determine if there is a better way to do this honestly. — jeremykrall
– jeremykrall, Commented Feb 23, 2017 at 4:53
You're ignoring the "results" and "pageData" fields, which contain the actual data. — Cihan Tek
– Cihan Tek, Commented Feb 23, 2017 at 4:54
Update your question with your attempt to access the desired data below results and pageData. — rmaddy
– rmaddy, Commented Feb 23, 2017 at 4:56

Nirav D · Accepted Answer · 2017-02-23 04:59:13Z

4

To access the info and categories dictionaries you need to first access results Array and pageData that is inside the first object of results array.

guard let json = json, let results = json["results"] as? [[String:Any]], 
    let firstDic = results.first, let pageData = firstDic["pageData"] as? [String:Any],
    let info = pageData["info"] as? [String:Int], let version = info["version"], 
    let categories = Category.getCategories(json: pageData) else {

    self.completionParse(RequestResult.errorParsing, self.categoriesResult)
    return
}

answered Feb 23, 2017 at 4:59

Nirav D

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3 Comments

jeremykrall Over a year ago

This took me down the right path, thanks very much for the help.

Nirav D Over a year ago

@jeremykrall Don't get you aren't you able to get version and categories with my solution or Am i missing something?

jeremykrall Over a year ago

Ended up with ` guard let json = json, let results = json["results"] as? [[String:Any]], let result = results.first, let pageData = result["pageData"] as? [String:Any], let info = pageData["info"] as? [String:Int], let version = info["version"], let categories = Category.getCategories(json: pageData) else { self.completionParse(RequestResult.errorParsing, self.categoriesResult) return } `

rmaddy · Accepted Answer · 2017-02-23 14:51:50Z

Tested below code on playground. This code is in latest swift 3.

if let dictResponse = json as? [String:Any] {
    // This will get entire dictionary from your JSON.
    if let results = dictResponse["results"] as? [[String:Any]]{
        if let pageData = results.first? ["pageData"] as? [String:Any]{
            if let info = pageData["info"] as? [String:Any]{
                if let version = info["version"] as? String{
                    print(version)
                    // This will print 1
                }
            }

            if let categories = pageData["categories"] as? [[String:Any]]{
                // This will give you a category array. Later on you can iterate and get the dictionary’s value of each element.
                for categoriesObj in categories.enumerated(){
                    if let name = categoriesObj.element["name"]{
                        print(name)
                    }
                }
            }           
        }   
    }
}

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