Cannot parse json array as nsarray in swift 2

Question

I have the following json as a response :

[
{
    "id_post": "1",
    "id_type": "1",
    "title": "I hffjj",
    "body": "nothing at all",
    "visitors": "0",
    "extrabutton": "none",
    "deviceid": "468af7f24ade50c9"
},
{
    "id_post": "2",
    "id_type": "1",
    "title": "suxk my ",
    "body": "sssusushshd",
    "visitors": "0",
    "extrabutton": "none",
    "deviceid": "468af7f24ade50c9"
}
]

I am trying to parse it as an NSArray as the following :

let task = session.dataTaskWithRequest(request) { data, response, error in
            guard data != nil else {
                print("no data found: \(error)")
                return
            }

            do {
                if let jsonResult = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers) as? NSArray {
                    print("Success: \(jsonResult)")
                }
            } catch let parseError {
                print(parseError)
            }
        }

I always get the error:

Error Domain=NSCocoaErrorDomain Code=3840 "JSON text did not start with array or object and option to allow fragments not set." UserInfo={NSDebugDescription=JSON text did not start with array or object and option to allow fragments not set.}

What am I doing wrong?

Minor point, but if you change your guard to guard let data = data else { .... } you can do away with the exclamation marks in the following code. — JeremyP
– JeremyP, Commented Sep 2, 2015 at 9:55

ChintaN -Maddy- Ramani · Accepted Answer · 2015-09-02 11:39:35Z

2

I think you try this one and use allow NSJSONReadingOptions.AllowFragments options which give you a proper json

let task = session.dataTaskWithRequest(request) { data, response, error in guard data != nil else {
           print("no data found: \(error)")
            return
           }

        do {
            if let jsonResult = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.AllowFragments | NSJSONReadingOptions.MutableContainers, error: nil) as? NSArray {
                print("Success: \(jsonResult)")
            }
        } catch let parseError {
            print(parseError)
            let jsonStr = NSString(data: data!, encoding: NSUTF8StringEncoding)
            print("Error could not parse JSON: '\(jsonStr)'")
        }
    }

edited Sep 2, 2015 at 11:39

ChintaN -Maddy- Ramani

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answered Sep 2, 2015 at 10:17

VSP

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3 Comments

xanyi Over a year ago

Another error: Binary operator cannot be applied to two NSJSONReadingOptions operands.

vacawama Over a year ago

Try options:[.AllowFragments, .MutableContainers]. The syntax changed in Swift 2.

xanyi Over a year ago

The options worked, the error is "Error Domain=NSCocoaErrorDomain Code=3840 "Invalid value around character 0." UserInfo={NSDebugDescription=Invalid value around character 0.}" now.

JeremyP · Accepted Answer · 2015-09-02 10:06:37Z

1

The data you get back is clearly not a UTF-8 string containing JSON. We can see this because the string appears to be set to

Current character set: utf8
NULL

when the error message is printed out.

I'd start by issuing the URL request from an ordinary web browser to make sure that the response is what you expect.

answered Sep 2, 2015 at 10:06

JeremyP

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2 Comments

xanyi Over a year ago

The response is what I expect. My problem isn't the utf8 encoding but the "JSON text did not start with array or object and option to allow fragments not set." utf8 is in the error handling branch

JeremyP Over a year ago

@xanyi Yesterday your question contained a second error message which printed out the content of the data which was clearly not a JSON string. Why do you think this is not relevant? It would cause exactly the problem you are seeing,

xhinoda · Accepted Answer · 2017-08-08 17:56:36Z

-1

For swift 3 and Xcode 8.1 you can use this:

 let jsonResult = try JSONSerialization.jsonObject(with: data!, options: [.allowFragments, .mutableContainers])

answered Aug 8, 2017 at 17:56

xhinoda

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1 Comment

vadian Over a year ago

The JSON in the question doesn't need any of those options and .mutableContainers is meaningless in Swift anyway.

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