Swift POST to api - swift

Question

I have an odd issue and I am hoping you guys can help me.
The Task:
I want to post json to a API rest call.
And I am sure the rest API works - I have copied the json from print() in Swift and tried it in postman, and the works just fine.
When I try to post via Swift i get 400 Bad request.
The code:
func postMobileContacts(serverURL: String, jsonToPost: String){
// Prepare URL
let url = URL(string: serverURL)
guard let requestUrl = url else { fatalError() }
// Prepare URL Request Object
var request = URLRequest(url: requestUrl)
request.httpMethod = "POST"
// Set HTTP Request Body
request.httpBody = Data(jsonToPost.utf8);
// Set HTTP Request Header
request.setValue("application/json", forHTTPHeaderField: "Accept")
request.setValue("application/json", forHTTPHeaderField: "Content-Type")
request.setValue("Authorization", forHTTPHeaderField: String(data: KeychainHelper.standard.read(service: "access-token", account: "store")!, encoding: .utf8)!)
// Perform HTTP Request
let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
// Check for Error
if let error = error {
print("Error took place \(error)")
return
}
// Convert HTTP Response Data to a String
if let data = data, let dataString = String(data: data, encoding: .utf8) {
print("Response data string:\n \(dataString)")
}
}
task.resume()
}

Answer 1

This line is definitely wrong:
request.setValue("Authorization", forHTTPHeaderField: String(data: KeychainHelper.standard.read(service: "access-token", account: "store")!, encoding: .utf8)!)
it should be the other way around.
request.setValue(String(data: KeychainHelper.standard.read(service: "access-token", account: "store")!, encoding: .utf8)!, forHTTPHeaderField: "Authorization")
You mixed up the value with the header name.

Answer 2

Made some edits to your code
Currently the data is not directly sent to the request as said in comments.
JSONEncodable can be send to the request after encoding to data.
func postMobileContacts(serverURL: String, jsonToPost: Encodable) { //<--here
// Prepare URL
let url = URL(string: serverURL)
guard let requestUrl = url else { fatalError() }
let data = try! JSONEncoder().encode(jsonToPost) //<-Changed here
// Prepare URL Request Object
var request = URLRequest(url: requestUrl)
request.httpMethod = "POST"
// Set HTTP Request Body
request.httpBody = data; //<-- and here
// Set HTTP Request Header
request.setValue("application/json", forHTTPHeaderField: "Accept")
request.setValue("application/json", forHTTPHeaderField: "Content-Type")
request.setValue("Authorization", forHTTPHeaderField: String(data: KeychainHelper.standard.read(service: "access-token", account: "store")!, encoding: .utf8)!)
// Perform HTTP Request
let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
// Check for Error
if let error = error {
print("Error took place \(error)")
return
}
// Convert HTTP Response Data to a String
if let data = data, let dataString = String(data: data, encoding: .utf8) {
print("Response data string:\n \(dataString)")
}
}
task.resume()
}