Question

我从这个网站获得了教程：http://jamesleist.com/ios-swift-tutorial-stop-segue-show-alert-text-box-empty/

这是我目前的代码。它只是不起作用，导致应用程序崩溃，因为如果任何字段为空，则下一个ViewController崩溃。

import Foundation
import UIKit
import Darwin

class View3on3 : UIViewController, UITextFieldDelegate {


@IBOutlet weak var APTeams: UITextField!
@IBOutlet weak var APRounds: UITextField!
@IBOutlet weak var APBreakers: UITextField!

var AP1: String = String()
var AP2: String = String()
var AP3: String = String()


override func viewDidLoad()
{
    super.viewDidLoad()
    initializeTextFields()
}


func initializeTextFields()
{
    APTeams.delegate = self
    APTeams.keyboardType = UIKeyboardType.NumberPad

    APRounds.delegate = self
    APRounds.keyboardType = UIKeyboardType.NumberPad

    APBreakers.delegate = self
    APBreakers.keyboardType = UIKeyboardType.NumberPad
}



@IBAction func userTappedBackground(sender: AnyObject)
{
    view.endEditing(true)
}

override func shouldPerformSegueWithIdentifier(identifier: String!, sender: AnyObject!) -> Bool {
    if identifier == "segueTest" {

        if (APTeams.text!.isEmpty) {

            let alert = UIAlertView()
            alert.title = "No Text"
            alert.message = "Please Enter Text In The Box"
            alert.addButtonWithTitle("Ok")
            alert.show()

            return false
        }

        else {
            return true
        }
    }

    // by default, transition
    return true

}


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

        if (segue.identifier == "segueTest"){

            var passs = segue.destinationViewController as! View3on3Results

                passs.AP1 = APTeams.text!
                passs.AP2 = APRounds.text!
                passs.AP3 = APBreakers.text!
        }


}
}

我尝试在SO上查看其他问题，但解决方案都出错了。我认为这是由于Swift更新到2.0。我可能是错的 - 这是非常新的。

Answer 1

我希望可能是因为AlertView。在swift 2.0中，UIAlertController取代了UIAlertView：

let alertController: UIAlertController = UIAlertController(title: "Hello", message: "Are you sure?", preferredStyle: UIAlertControllerStyle.Alert)

let okAction = UIAlertAction(title: "Yes", style: UIAlertActionStyle.Default, handler: nil)

alertController.addAction(okAction)

presentViewController(alertController, animated: true, completion: nil)

使用上面的代码将UIAlertView替换为UIAlertViewController。

编辑：

同时制作IBOutlet选项：

@IBOutlet weak var APTeams: UITextField?
@IBOutlet weak var APRounds: UITextField?
@IBOutlet weak var APBreakers: UITextField?

Answer 2

我认为如果segue不是performSegueWithIdentifier，那么应该使用textfield手动拨打empty，如果是alert

您的代码可能看起来像[在提交您的数据时可能会点击按钮，或者尝试在<{1}}之后或将此代码置于viewDidLoad内

initializeTextFields()

如果我没错，你就不需要if(APTeams.text!.isEmpty){ // your code for showing alert. You can use UIAlertController if UIAlertView is not working. } else { self.performSegueWithIdentifier("segueTest",sender: View3on3Results.self) }。

Answer 3

解决！这是有效的代码。感谢@SohilRMemon和@FrequencyMatched帮助我把它放在一起。

代码在这里：

import Foundation
import UIKit
import Darwin

class View3on3 : UIViewController, UITextFieldDelegate {


@IBOutlet weak var APTeams: UITextField!
@IBOutlet weak var APRounds: UITextField!
@IBOutlet weak var APBreakers: UITextField!

var AP1: String = String()
var AP2: String = String()
var AP3: String = String()


override func viewDidLoad()
{
    super.viewDidLoad()
    initializeTextFields()
}


func initializeTextFields()
{
    APTeams.delegate = self
    APTeams.keyboardType = UIKeyboardType.NumberPad

    APRounds.delegate = self
    APRounds.keyboardType = UIKeyboardType.NumberPad

    APBreakers.delegate = self
    APBreakers.keyboardType = UIKeyboardType.NumberPad
}


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

        if (APTeams.text!.isEmpty || APRounds.text!.isEmpty || APBreakers.text!.isEmpty)
        {

            let alertController: UIAlertController = UIAlertController(title: "Hello", message: "Are you sure?", preferredStyle: UIAlertControllerStyle.Alert)

            let okAction = UIAlertAction(title: "Yes", style: UIAlertActionStyle.Default, handler: nil)

            alertController.addAction(okAction)

            presentViewController(alertController, animated: true, completion: nil)
        }

        else
        {
            let DestViewController : View3on3Results = segue.destinationViewController as! View3on3Results

            DestViewController.AP1 = APTeams.text!
            DestViewController.AP2 = APRounds.text!
            DestViewController.AP3 = APBreakers.text!

            //self.performSegueWithIdentifier("segueTest",sender: View3on3Results.self)//
        }



        }

}

取消Segue并显示警告 - Xcode

3 个答案: