POST request not being sent in Swift - swift

Question

I would just like to ask. Why is my POST request below not being sent? The code seems perfectly sound, and Xcode shows no errors. I am using Swift 3. Could you please help me? Thanks! My code is below, my post URL is here. Thanks again!
#IBAction func onClick(_ sender: Any) {
let username = Username.text
let password = Password.text
let request = NSMutableURLRequest(url: url)
request.httpMethod = "POST"
let params = ["username": username, "password": password] as Dictionary<String, AnyObject>
do {
try request.httpBody = JSONSerialization.data(withJSONObject: params, options: .prettyPrinted)
} catch {
print("Error")
}
request.addValue("application/JSON", forHTTPHeaderField: "Content-Type")
URLSession.shared.getAllTasks { (openTasks: [URLSessionTask]) in
NSLog("open tasks: \(openTasks)")
}
}

Answer 1

You need to use:
let task = session.dataTaskWithRequest(urlRequest, completionHandler: { (data, response, error) in
// do stuff with response, data & error here
print(error)
print(response)
})
task.resume()
Get more info here

Answer 2

You have to use URLSession.shared.dataTask(with:completionHandler:). Also, don't use NSMutableRequest, but use the native Swift version, URLRequest.
#IBAction func onClick(_ sender: Any) {
let username = Username.text
let password = Password.text
var request = URLRequest(url: url)
request.httpMethod = "POST"
let params = ["username": username, "password": password] as Dictionary<String, AnyObject>
do {
try request.httpBody = JSONSerialization.data(withJSONObject: params, options: .prettyPrinted)
} catch {
print("Error")
}
request.addValue("application/JSON", forHTTPHeaderField: "Content-Type")
URLSession.shared.dataTask(with: request, completionHandler: { data,response, error in
if let existingError = error {
//handle error
}
//handle response and/or data
}).resume()
}