Post request with JSON body in Swift - swift

Question

I have been looking for a similar solution for a long time but I can't find it.
I have to make a post request for my Stripe server.
For that I have to send a request with a JSON in Body : {"price" : 50}.
I can't figure out what's wrong.
Thank you
override func viewDidLoad() {
super.viewDidLoad()
checkoutButton.addTarget(self, action: #selector(didTapCheckoutButton), for: .touchUpInside)
checkoutButton.isEnabled = false
let parameters: [String: Any] = [
"price": "50",
]
let jsonData = try? JSONSerialization.data(withJSONObject: parameters)
var request = URLRequest(url: backendCheckoutUrl)
request.httpMethod = "POST"
request.setValue("\(String(describing: jsonData?.count))", forHTTPHeaderField: "Content-Length")
request.setValue("application/json", forHTTPHeaderField: "Content-Type")
request.httpBody = jsonData
let task = URLSession.shared.dataTask(with: request, completionHandler: { [weak self] (data, response, error) in
guard let data = data,
let json = try? JSONSerialization.jsonObject(with: data, options: []) as? [String : Any],
let customerId = json["customer"] as? String,
let customerEphemeralKeySecret = json["ephemeralKey"] as? String,
let paymentIntentClientSecret = json["paymentIntent"] as? String,
let publishableKey = json["publishableKey"] as? String,
let self = self else {
return
}
STPAPIClient.shared.publishableKey = publishableKey
var configuration = PaymentSheet.Configuration()
configuration.merchantDisplayName = "Example, Inc."
configuration.applePay = .init(
merchantId: "com.foo.example", merchantCountryCode: "US")
configuration.customer = .init(
id: customerId, ephemeralKeySecret: customerEphemeralKeySecret)
configuration.returnURL = "....."
configuration.allowsDelayedPaymentMethods = true
self.paymentSheet = PaymentSheet(
paymentIntentClientSecret: paymentIntentClientSecret,
configuration: configuration)
DispatchQueue.main.async {
self.buyButton.isEnabled = true
}
})
task.resume()
}