sending get / put / post in swift - swift

Question

I can easily issue a GET request and it returns (as expected) JSON data that is decoded to myDataModel object:
class func getData(completionHandler: #escaping (myDataModel?, Error?) -> Void)
{
let url = "https://example.com/api/someResource?ws_key=ABC...XYZ"
if let myUrl = URL(string: url)
{
URLSession.shared.dataTask(with: myUrl)
{
(data, response, err) in
if let data = data
{
do
{
let result = try JSONDecoder().decode(myDataModel.self, from: data)
completionHandler(result, nil)
}
catch let JSONerr
{
completionHandler(nil, JSONerr)
}
}
}.resume()
}
}
This work fine, so GET is no problem. (PS. the above has been simplified and modified.)
Likewise, I can issue a POST request and it returns (as expected) JSON data, when I use parameters like key1=value1&key2=value2. (I read that the default POST Content-Type is application/x-www-form-urlencoded.)
However, in another application I need to POST a piece of XML. After many tries and getting many errors, the approach I'm using is to: Set the header Content-Type to text/xml; charset=utf-8; Have no parameters and send the XML as the request body. I use a refined method:
PostHTTP(url: "https://example.com/api/someResource?ws_key=ABC...XYZ",
parameters: nil,
headers: ["Content-Type": "text/xml; charset=utf-8", "Content-Length": "\(xml.count)"],
body: "\(xml)") { (result) in ... }
(I image that you can determine what happens behind the scenes.)
For the POST request, to send a piece of XML:
Do I need to set the Content-Length or is this automatic?
Can I send parameters with the XML?
What headers (like Content-Type) do I require?
What structure (eg. xml=<?xml...) and encoding (eg. addingPercentEncoding) do I require?
Also I need to PUT data and I have similar method. The response from my attempt has the error
String could not be parsed as XML, XML length: 0
For a PUT request:
What headers (like Content-Type) do I require?
What structure (eg. xml=<?xml...) and encoding (eg. addingPercentEncoding) do I require?
Since I have tried many ways, an example of both PUT and POST would be ideal.

Answer 1

If you want to send data of XML you can do this in both PUT and POST
It does not have to be determined Content-Length
But you must add Content-Type
let req = NSMutableURLRequest(url: URL(string:"myUrl")!)
req.httpMethod = "POST"
req.setValue("application/xml;charset=utf-8;", forHTTPHeaderField: "Content-Type")
req.setValue("application/xml;", forHTTPHeaderField: "Accept")
var postBody = Data()
if let anEncoding = ("<?xml version='1.0' encoding='UTF-8'?>").data(using: .utf8) {
postBody.append(anEncoding)
}
if let anEncoding = "<Request>".data(using: .utf8) {
postBody.append(anEncoding)
}
if let anEncoding = "<test>\(123)</test>".data(using: .utf8) {
postBody.append(anEncoding)
}
if let anEncoding = "</Request>".data(using: .utf8) {
postBody.append(anEncoding)
}
req.httpBody = postBody
req.setValue("\(postBody.count)", forHTTPHeaderField: "Content-Length")
URLSession.shared.dataTask(with: req as URLRequest) { (data, urlreq, error) in
}