Question 66532 in IOS Swift Question posted in
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Decode JSON in Swift "The given data was not valid JSON." – Ios swift

I’m writing a swift program and I need to use an API to get the response.
Here is the API url: http://text-processing.com/api/sentiment/
document: http://text-processing.com/docs/sentiment.html

When I test it on terminal, it works well:
//command in terminal

curl -d "text=great" http://text-processing.com/api/sentiment/

//what I got

{"probability": {"neg": 0.30135019761690551, "neutral": 0.27119050546800266, "pos": 0.69864980238309449}, "label": "pos"}

But when I want to decode the response data in Swift, it failed.

My codes are attached as following:

struct Result : Codable{
    var probability: Probability
    var label: String
    struct Probability: Codable{
        var neg: Double
        var neutral: Double
        var pos: Double
    }
}

class ResponseData: ObservableObject{
    @Published var result: [Result] = []
    func API()-> Bool{
        guard let url = URL(string: "http://text-processing.com/api/sentiment/") else { fatalError("Missing URL") }
        var request = URLRequest(url: url)
        request.setValue("text=great", forHTTPHeaderField: "Content-Type")
        request.httpMethod = "POST"

        let session = URLSession.shared
        let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
            if (error != nil) {
                print(error)
            } else {
                let httpResponse = response as? HTTPURLResponse
                print(httpResponse)
                guard let data = data else { return }
                DispatchQueue.main.async {
                do {
                    let decodedResult = try JSONDecoder().decode(Result.self, from: data)
                    self.result = [decodedResult]
                    print(self.result)
                        } catch let error {
                            print("Error decoding: ", error)
                    }
                }
            }
        })

        dataTask.resume()
        return true
    }
}

The error is:

Error decoding:  dataCorrupted(Swift.DecodingError.Context(codingPath: [], debugDescription: "The given data was not valid JSON.", underlyingError: Optional(Error Domain=NSCocoaErrorDomain Code=3840 "Invalid value around line 1, column 0." UserInfo={NSDebugDescription=Invalid value around line 1, column 0., NSJSONSerializationErrorIndex=0})))

I have searched a lot but could not find an available solution. Could anyone share some idea? Thanks a lot.

Tags:

2

Answers


  1. 0

    You’re requesting invalid request.

    request.setValue("text=great", forHTTPHeaderField: "Content-Type")

    is not correct, you have to send it as body in form-url-encoded

    request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
request.httpBody = Data("text=great".utf8)
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  2. 0

    You need to identify where lies your issue:

    So let’s print what you in fact receive:

    print("Data Str: (String(data: data, encoding: .utf8))")

    That gives:

    $> Data Str: Optional("Form Validation Errorsntext: This field is required.n")

    So your JSON Decoding files because you didn’t receive the expected output, it’s not even JSON.

    Now, let’s see the working cURL Sample:

    curl -d "text=great" http://text-processing.com/api/sentiment/

    The -d is for httpBody, not as your write for headers. If that were the case, you would have -H 'Content-Type: text=great'. Yours doesn’t make sense at all, as what means "Content-Type" parameter in requests.

    So, the request creation should be:

    var request = URLRequest(url: url)
request.httpBody = Data("text=great".utf8)
request.httpMethod = "POST"
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