Post file to server - Swift - html

Question

First off, I know, there are a lot of questions on this topic, but I still don't get it.
Inside my iOS app, I want to post a string to a file on my server. I found many ways to do that online and went with the following:
func postBookingNumber() {
var request = URLRequest(url: URL(string: "http://myServerURL.com/booking-number.txt")!)
request.httpMethod = "POST"
let postString = "date=\(Date())&booking-number=\(self.getBookingNumber())" //returns string with format: "01"
request.httpBody = postString.data(using: .utf8)
let task = URLSession.shared.dataTask(with: request) { data, response, error in
guard let data = data, error == nil else {
print("error=\(error)")
return
}
if let httpStatus = response as? HTTPURLResponse, httpStatus.statusCode != 200 {
print("statusCode should be 200, but is \(httpStatus.statusCode)")
print("response = \(response)")
}
let responseString = String(data: data, encoding: .utf8)
print("responseString = \(responseString)")
}
task.resume()
}
Now, the file on the server is currently emtpy, until I post something to it. My plan was to either append the new booking number string to the file, OR downloading the file, appending the new booking number string to it and replacing the online version with the one I just edited inside my app.
Questions
Does the code above & my strategy make any sense?
How do I handle the "date=\(Date())&booking-number=\(self.getBookingNumber())" request on the server side?
Can I go with HTML or do I have to use JS? PHP?
I'm an absolute beginner when it comes to server stuff, so please be kind :)
Thanks in advance!