CODEWITHSUNDEEP
iosjsonswift
ddesai
ddesai

Reputation: 519

count occurrences of a key in JSON data

I want to count number of "items" in my json result for me to loop on it. Please see the code below which doesn't work for me:

var jsonResult:NSDictionary = NSJSONSerialization.JSONObjectWithData(data, options: .MutableContainers, error: nil) as NSDictionary
for var i = 0; i < jsonResult["items"].count; i++ {}

It gives me following compile error: "AnyObject? doesnt have a member named count"

Can you please help me understand the reason behind it? and also, Can you please let me know the work around it?

Thanks for your help

Upvotes: 0

Views: 457

Answers (2)

Leo
Leo

Reputation: 24714

Because jsonResult["items"] this returnAnyObject? ,you have to convert it to real class it is.For example

 var dic:NSMutableDictionary = NSMutableDictionary()
    dic.setValue(["first","second","third"], forKey: "items")
    var json:NSData = NSJSONSerialization.dataWithJSONObject(dic, options: NSJSONWritingOptions.PrettyPrinted, error: nil)!
    var jsondic = NSJSONSerialization.JSONObjectWithData(json, options:NSJSONReadingOptions.MutableContainers, error: nil) as NSDictionary
    var jsonItems = jsondic["items"] as NSArray
    for var i = 0;i < jsonItems.count; i++ {
        println(jsonItems[i] as String)
    }

This is the key 

        var jsonItems = jsondic["items"] as NSArray

You may use "as?",so that if convert fail,you app will not crash

  var jsonItems = jsondic["items"] as? NSArray
        if(jsonItems != nil){
            for var i = 0;i < jsonItems!.count; i++ {
                println(jsonItems![i] as String)
            }
        }

Upvotes: 1

robinkunde
robinkunde

Reputation: 1000

Because you're parsing dynamic data, the compiler can't make guarantees about what the JSON parser returns at runtime. For that reason, any value you retrieve from a JSON object is an optional you have to explicitly unwrap.

You can read about it at http://www.atimi.com/simple-json-parsing-swift-2/.

I believe there are libraries for JSON parsing in Swift now, that make this type of stuff a lot easier.

Upvotes: 2

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