@IBOutlet weak var usernameTextField: UITextField!
// `passwordTextField.secureTextEntry = true`
@IBOutlet weak var passwordTextField: UITextField!
@IBOutlet weak var webView: UIWebView!

...

@IBAction func signIn(sender: AnyObject) {
    var url = NSURL(string: "http://webgiz.faqserv.com/webgiz/index.php")
    var request = NSMutableURLRequest(URL: url!)
    request.HTTPMethod = "POST"

    // Get the user's credentials from the `UITextField`s
    var username: String = usernameTextField.text
    var password: String = passwordTextField.text

    // Concatenating everything together
    var userCredentials: String = "username=(username)&password=(password)&userType=A" // add all parameters needed
    var bodyData: String = "(userCredentials)"

    // Encode the bodyData string into a
    request.HTTPBody = bodyData.dataUsingEncoding(NSUTF8StringEncoding)

    // load the UIWebView `webView` with this request
    webView.loadRequest(request)
}