Swift：编程方式导航到ViewController并传递数据

Question

我最近开始学习Swift，到目前为止进展还不错。目前我遇到了一个问题，就是如何在视图控制器之间传递数据。我已经想出了如何使用导航控制器以编程方式在两个视图控制器之间导航的方法。唯一的问题是现在我很难弄清楚如何将用户输入的三个字符串（用于JSON API）传递到下一个视图。

以下是我的当前尝试，非常感谢任何帮助！

ViewController：

/* Get the status code of the connection attempt */
func connection(connection:NSURLConnection, didReceiveResponse response: NSURLResponse){

    let status = (response as! NSHTTPURLResponse).statusCode
    //println("status code is \(status)")

    if(status == 200){

        var next = self.storyboard?.instantiateViewControllerWithIdentifier("SecondViewController") as! SecondViewController
        self.presentViewController(next, animated: false, completion: nil)
    }
    else{

        RKDropdownAlert.title("Error", message:"Please enter valid credentials.", backgroundColor:UIColor.redColor(), textColor:UIColor.whiteColor(), time:3)
        drawErrorBorder(usernameField);
        usernameField.text = "";
        drawErrorBorder(passwordField);
        passwordField.text = "";
    }
}

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject!) {

    let navigationController = segue.destinationViewController as! UINavigationController
    let newProjectVC = navigationController.topViewController as! SecondViewController
    newProjectVC.ip = ipAddressField.text
    newProjectVC.username = usernameField.text
    newProjectVC.password = passwordField.text
}

SecondViewController:

import UIKit

class SecondViewController: UIViewController {

var ip:NSString!
var username:NSString!
var password:NSString!

override func viewDidLoad() {
    super.viewDidLoad()

    println("\(ip):\(username):\(password)")
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}
}

- user3459799

Answer 1

prepareForSegue方法在你的应用Storyboard执行segue（使用Interface Builder创建的连接）时被调用。但是，在上述代码中，您是使用presentViewController自己呈现控制器的。在这种情况下，prepareForSegue不会被触发。您可以在呈现控制器之前进行设置：

let next = self.storyboard?.instantiateViewControllerWithIdentifier("SecondViewController") as! SecondViewController
next.ip = ipAddressField.text
next.username = usernameField.text
next.password = passwordField.text
self.presentViewController(next, animated: false, completion: nil)

您可以在此处阅读有关segue的更多信息：这里。

- andreamazz

Answer 2

Swift 3更新语法：

    let next = self.storyboard?.instantiateViewController(withIdentifier: "SecondViewController") as? SecondViewController 
    next.ip = ipAddressField.text
    next.username = usernameField.text
    next.password = passwordField.text
    self.present(next, animated: true, completion: nil)

- Ty Victorson