如何使用Swift的NSURL格式化HTML，PHP

Question

I am attempting to connect to a MySQL database with Swift through PHP by getting the HTML of a PHP script. I plan on using the URL to pass variables such as username, password, or id to the PHP script then call the MySQL. However, whenever I attempt to get the response of a webpage with NSURL an error occurs. Here is the code I am using:

let myUrl = NSURL(string: "http://www.google.com")
    let request = NSMutableURLRequest(URL: myUrl!)
    request.HTTPMethod = "POST"
    let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {
        data, response, error in
        let responseString = NSString(data: data!, encoding: NSUTF8StringEncoding)
        if error != nil {
            print("Error: \(error)")
        }
        print("Response: \(response)")
        print("Response String: \(responseString)")
    }
    task.resume()

Do I need to format the output from the website to be properly transferred to Swift? Thank you for the help.

Answer 1

Your code runs in Xcode 7.1's playground without producing any errors. In order to let asynchronous code execute in playground I added 2 lines. Try it yourself. So I guess the problem lies in your server.

import Foundation
import XCPlayground

// Let asynchronous code run
XCPlaygroundPage.currentPage.needsIndefiniteExecution = true

let myUrl = NSURL(string: "http://www.google.com")
let request = NSMutableURLRequest(URL: myUrl!)
request.HTTPMethod = "POST"
let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {
  data, response, error in
  let responseString = NSString(data: data!, encoding: NSUTF8StringEncoding)
  if error != nil {
    print("Error: \(error)")
  }
  print("Response: \(response)")
  print("Response String: \(responseString)")
}
task.resume()

If you can't figure out what's wrong, sharing the error message will help others find out what's happened.

UPDATE: I tried your code in a iOS project the code crashes because you are not checking if the data is nil and just unwrapping it at this line:

let responseString = NSString(data: data!, encoding: NSUTF8StringEncoding)

But why the data turns out to be nil? It is because App Transport Security in iOS 9 does not allow you to use HTTP by default. Your server has to be HTTPS with TLS v1.2 or higher. To allow HTTP requests, refer to this: Configuring App Transport Security Exceptions in iOS 9 and OSX 10.11

Also you should check the error before using the data to avoid crash.

let myUrl = NSURL(string: "http://www.google.com")
let request = NSMutableURLRequest(URL: myUrl!)
request.HTTPMethod = "POST"
let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {
  data, response, error in
  // Check error before using the data
  if error != nil {
    print("Error: \(error)")
    return
  }
  let responseString = NSString(data: data!, encoding: NSUTF8StringEncoding)
  print("Response: \(response)")
  print("Response String: \(responseString)")
}
task.resume()