let request = NSMutableURLRequest(URL: NSURL(string: address)!)
        request.HTTPMethod = "POST"
        let postString = "username=" + idStr! + "&password=" + pwStr!
        request.HTTPBody = postString.dataUsingEncoding(NSUTF8StringEncoding)

        let task = NSURLSession.sharedSession().dataTaskWithRequest(request, completionHandler: {data, response, error in
            if (error == nil) {
                do {
                    let result = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers)

                    if (result["fields"] != nil && result["fields"] as? NSNumber == 1) {
                        if (result["exist"] != nil && result["exist"] as? NSNumber == 1) {
                            if (result["success"] != nil && result["success"] as? NSNumber == 1) {
                                dispatch_async(dispatch_get_main_queue(), { ()->Void in
                                    let prefs:NSUserDefaults = NSUserDefaults.standardUserDefaults()
                                    prefs.setBool(true, forKey: "isLoggedIn")
                                    prefs.setValue(self.idInput.text!, forKey: "username")
                                    prefs.setValue(result.valueForKey("name") as! String, forKey: "name")
                                    prefs.setValue(result.valueForKey("birth") as! String, forKey: "birth")
                                    prefs.setValue(result.valueForKey("phone") as! String, forKey: "phone")
                                    prefs.setValue(result.valueForKey("email") as! String, forKey: "email")
                                    prefs.setValue(result.valueForKey("church_name") as! String, forKey: "churchName")
                                    prefs.setValue(result.valueForKey("church_type") as! String, forKey: "churchType")
                                    prefs.setValue(result.valueForKey("church_duty") as! String, forKey: "churchDuty")
                                    self.performSegueWithIdentifier("showMain", sender: self)
                                })

                            } else {
                                NSOperationQueue.mainQueue().addOperationWithBlock {
                                    let alert = UIAlertController(title: "Login Failed", message: "Wrong password", preferredStyle: UIAlertControllerStyle.Alert)
                                    alert.addAction(UIAlertAction(title: "Confirm", style: UIAlertActionStyle.Default, handler: nil))
                                    self.presentViewController(alert, animated: true, completion: nil)
                                }
                            }
                        } else {
                            NSOperationQueue.mainQueue().addOperationWithBlock {
                                let alert = UIAlertController(title: "Login failed", message: "Username is not existed", preferredStyle: UIAlertControllerStyle.Alert)
                                alert.addAction(UIAlertAction(title: "Confirm", style: UIAlertActionStyle.Default, handler: nil))
                                self.presentViewController(alert, animated: true, completion: nil)
                            }
                        }
                    } else {
                        NSOperationQueue.mainQueue().addOperationWithBlock {
                            let alert = UIAlertController(title: "Login Failed", message: "Connection Failed", preferredStyle: UIAlertControllerStyle.Alert)
                            alert.addAction(UIAlertAction(title: "Confirm", style: UIAlertActionStyle.Default, handler: nil))
                            self.presentViewController(alert, animated: true, completion: nil)
                        }
                    }
                } catch let error as NSError {
                    print (error.localizedDescription)
                }
            } else {
                print (error)
            }
        })
        task.resume()