Swift - Send NSDictionary as parameter in POST - ios

Question

I am able to make a successful POST request in POSTMAN like this:
{
"id": "1",
"myDictKey": {
"key0": "blah",
"key1": "blah",
"key2": "blah"
}
}
However, when I try to make this POST request in swift, the POST is unsuccessful. The NSDictionary param doesn't seem to get encoded as expected.
Swift Code
let dictParam = ["key0": "blah", "key1": "blah", "key2": "blah"] as NSDictionary
let urlString = MY_URL
let url = URL(string: urlString)!
var request = URLRequest(url: url)
request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
request.httpMethod = "POST"
let parameters: [String: Any] = [
"id": "1",
"myDictKey": dictParam
]
request.httpBody = parameters.percentEncoded()
let task = URLSession.shared.dataTask(with: request) { data, response, error -> Void in
if error != nil {
completion(nil, error?.localizedDescription)
return
}
do {
if let json = try JSONSerialization.jsonObject(with: data!, options: [.allowFragments]) as? NSDictionary {
if response?.statusCode() == 200 {
if let jsonResponse = json.value(forKeyPath: "response") as? NSDictionary {
completion(jsonResponse, nil)
return
} else if response?.statusCode() == 401 {
completion(nil, "Unauthorized")
} else {
completion(nil, "Something went wrong. Try again later")
}
}
} catch {
completion(nil, "Something went wrong. Try again later")
}
}
task.resume()
percentEncoded()
// MARK: - Dictionary
extension Dictionary {
func percentEncoded() -> Data? {
return map { key, value in
let escapedKey = "\(key)".addingPercentEncoding(withAllowedCharacters: .urlQueryValueAllowed) ?? ""
let escapedValue = "\(value)".addingPercentEncoding(withAllowedCharacters: .urlQueryValueAllowed) ?? ""
return escapedKey + "=" + escapedValue
}
.joined(separator: "&")
.data(using: .utf8)
}
}
CharacterSet
// MARK: - CharacterSet
extension CharacterSet {
static let urlQueryValueAllowed: CharacterSet = {
let generalDelimitersToEncode = ":#[]#" // does not include "?" or "/" due to RFC 3986 - Section 3.4
let subDelimitersToEncode = "!$&'()*+,;="
var allowed = CharacterSet.urlQueryAllowed
allowed.remove(charactersIn: "\(generalDelimitersToEncode)\(subDelimitersToEncode)")
return allowed
}()
}

Answer 1

What you need is to JSONSerialize the parameter:
request.httpBody = try? JSONSerialization.data(withJSONObject: parameters, options: .prettyPrinted)

Answer 2

You can create Encodable model for your request body.
Something like this:
struct MyRequestBodyModel: Encodable {
let id: String
let myDictKey: MyNestedModel
}
struct MyNestedModel: Encodable {
let key0: String
let key1: String
let key2: String
}
And after:
do {
let requestBody = MyRequestBodyModel(...)
request.httpBody = try JSONEncoder().encode(requestBody)
} catch {
// Handle error here
}
I think this way is clearer and easier to maintain.