How to create JSON from a dictionary in Swift 4?

user_5898523 0
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Edit: I have read the other answers on SO for the same issue , however Im unable to get the desired output. I have tried many variations as suggested in other questions but its not working.

I have a JSON snipped which needs to be added as the body when I open a websocket.

sender: "system1@example.com",
recipients:"system2@example.com",
data: {
    text: "Test Message"
},

So using Swift I did the following,

var messageDictionary : [String: Any] = [
    "sender": "system1@example.com",
    "recipients":"system2@example.com",
    "data": [
        "text": "Test Message"
    ],
]
do {
    let jsonData = try JSONSerialization.data(withJSONObject: messageDictionary, options: .prettyPrinted)
    let jsonString = String(data: jsonData, encoding: String.Encoding.ascii)
    socket.write(string: jsonString!)
    print(jsonString)
} catch {
    print(error.localizedDescription)
}

When I print the jsonString, I get

Optional("{\n  \"sender\" : \"system1@example.com\",\n  \"data\" : {\n    
    \"text\" : \"Test Message\"\n  },\n  \"recipients\" : 
    \"system2@example.com\"\n}")

as the console output. I expected the above snippet to be formatted as JSON. How to get the output as normal JSON without the /n and additional spaces? Im using Swift 4 and Xcode 9.1

Edit 2:

let jsonData = try JSONSerialization.data(withJSONObject: messageDictionary, options: []) let decoded = try JSONSerialization.jsonObject(with: jsonData, options: [])

I tried doing the above and I get the following as the output:

{
    data =     {
        text = Test Message;
    };
    recipients = "system1@example.com";
    sender = "system2@example.com";
}

However the websocket expects this:

{ "sender":"system1@example.com","recipients":
["system2@example.com"],"data":{"text":"Test Message"}}

Even with a slight variation like misplacing of double quotes the websocket server doesnt accept the input. How to exactly format the JSOn this way so that the websocket can accept it?

swift nsdictionary json
3 Answers

After trying out various ways, the below way is what worked for me for getting the exact format required by the backend.

var messageDictionary = [
    "sender":"system1@example.com",
    "recipients":[
        "system2@example.com"
    ],
    "data":[
        "text" : data
    ]
] as [String : Any]

let jsonData = try! JSONSerialization.data(withJSONObject: messageDictionary)
let jsonString = NSString(data: jsonData, encoding: String.Encoding.utf8.rawValue)
user_58985230

Additionally, you can just cast to String

let jsonData = try? JSONSerialization.data(withJSONObject: dict, options: .prettyPrinted)
let jsonString = String(data: jsonData!, encoding: .utf8)
user_72809060

Now JSONEncoder can do the work easily.

let encoder = JSONEncoder()

encoder.outputFormatting = .prettyPrinted

let data = try encoder.encode(yourDictionary)

print(String(data: data, encoding: .utf8)!)
user_15062000
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