ios - 如果没有在 Swift 中的 TextField 中输入文本，则使 UIButton 处于非事件状态

Question

所以我的概念很简单，我有一个文本字段和一个标有“下一步”的按钮。如果用户没有在文本字段中放置任何内容，我希望对用户禁用“下一步”按钮。为此，我运行了这段代码:

 @IBAction func nextButton(sender: UIButton) {

    if textField.text.isEmpty {

        buttonLabel.userInteractionEnabled = false

    }
 }

这会按我的意愿禁用按钮，但问题是，如果随后在文本字段中输入文本，该按钮仍处于禁用状态。我试过在“if”语句之后添加“else”语句来反转我所说的，看看它是否有效，但它没有。

非常感谢任何帮助。

尼克

我的代码:

import UIKit

class ViewController: UIViewController, UITextFieldDelegate, UIPickerViewDataSource, UIPickerViewDelegate {

func imageEffect() {

    // Set vertical effect for background
    var verticalMotionEffect : UIInterpolatingMotionEffect =
    UIInterpolatingMotionEffect(keyPath: "center.y",
        type: .TiltAlongVerticalAxis)
    verticalMotionEffect.minimumRelativeValue = -20
    verticalMotionEffect.maximumRelativeValue = 20

    // Set horizontal effect for background
    var horizontalMotionEffect : UIInterpolatingMotionEffect =
    UIInterpolatingMotionEffect(keyPath: "center.x",
        type: .TiltAlongHorizontalAxis)
    horizontalMotionEffect.minimumRelativeValue = -20
    horizontalMotionEffect.maximumRelativeValue = 20

    // Create group for background to combine both
    var group : UIMotionEffectGroup = UIMotionEffectGroup()
    group.motionEffects = [horizontalMotionEffect, verticalMotionEffect]

    // Add both effects to your view for background
    myBackgroundView.addMotionEffect(group)

}

var datePickerView:UIDatePicker = UIDatePicker()

@IBAction func textFieldEdited(sender: UITextField) {

    var datePickerView  : UIDatePicker = UIDatePicker()
    datePickerView.datePickerMode = UIDatePickerMode.Date
    sender.inputView = datePickerView
    datePickerView.addTarget(self, action: Selector("handleDatePicker:"), forControlEvents: UIControlEvents.ValueChanged)

    }

func handleDatePicker(sender: UIDatePicker) {
    var dateFormatter = NSDateFormatter()
    dateFormatter.dateFormat = "dd MMMM yyyy"
    questionTextField.text = dateFormatter.stringFromDate(sender.date)
}

var countryData = ["United Kingdom", "France", "Spain", "Germany", "Berlin", "Eygpt", "United States"]

var pickerView:UIPickerView = UIPickerView()

@IBOutlet var progressStatus: UIProgressView!

@IBOutlet var barImage: UIImageView!

@IBOutlet var questionLabel: UILabel!

@IBOutlet var buttonBarImage: UIImageView!

@IBOutlet var buttonLabel: UIButton!

@IBOutlet var myBackgroundView: UIImageView!

@IBOutlet var questionTextField: UITextField!

let questions = ["Where are you going?", "What are you doing there?", "When do you go?"]

var currentQuestionIndex = 0

let placeholder = ["Country", "Activity", "Date"]

var currentPlaceholderIndex = 0

@IBAction func nextButton(sender: AnyObject) {

    if currentQuestionIndex == 0 {

        progressStatus.setProgress(0.333, animated: true)

    } else if currentQuestionIndex == 1 {

        progressStatus.setProgress(0.666, animated: true)

    } else {

        progressStatus.setProgress(1, animated: true)

    }

    // Initial setup on button press
    questionTextField.hidden = false
    barImage.hidden = false
    questionTextField.placeholder = placeholder[currentPlaceholderIndex]
    questionLabel.text = questions[currentQuestionIndex]
    questionTextField.resignFirstResponder()

    // Reset text field to have no text
    questionTextField.text = ""

    // Displays the questions in array and displays the placeholder text in the textfield
    if currentQuestionIndex <= questions.count && currentPlaceholderIndex <= placeholder.count {

        currentQuestionIndex++
        currentPlaceholderIndex++
        //progressStatus.setProgress(0.333, animated: true)
        buttonLabel.setTitle("Next", forState: UIControlState.Normal)


        // Animate text for questionLabel
        UIView.animateWithDuration(1.0, delay: 0.0, usingSpringWithDamping: 0.9, initialSpringVelocity: 0.5, options: nil, animations: {

            self.questionLabel.center = CGPoint(x: -110 , y: 305 + 20)

            }, completion: nil)

    } else {

        //Add some logic here to run whenever the user has answered all the questions.

    }

}


override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    questionTextField.delegate = self
    pickerView.delegate = self
    pickerView.dataSource = self

    // Applies the image effect to the image in myBackgroundImage
    imageEffect()

    // Sets the button text
    buttonLabel.setTitle("Get started", forState: UIControlState.Normal)

    // Sets the question text to be blank
    questionLabel.text = ""


    // Sets placeholder text in the text field
    questionTextField.placeholder = ""

    // Hides the text field
    questionTextField.hidden = true

    // Hides the image background for the text field
    barImage.hidden = true

    // Sets the progress bar to nil
    progressStatus.setProgress(0, animated: true)

    if questionTextField.text.isEmpty {

        buttonLabel.userInteractionEnabled = false
    }

}

func textFieldDidBeginEditing(textField: UITextField) {


    buttonLabel.userInteractionEnabled = true


    switch currentQuestionIndex {

    case 0:
        // TODO: Add UIPickerView
        self.view.addSubview(datePickerView)
    case 2:
        // TODO: Add UIDatePicker
        self.view.addSubview(datePickerView)

    default:
        println("default")
    }
}


// resigns the keyboard when user presses the return/next key on keyboard

func textFieldShouldReturn(textField: UITextField) -> Bool {

    questionTextField.resignFirstResponder()

    return true

}

func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {

    return 1
}

func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {

    return countryData.count

}

func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String! {
    return countryData[row]

}

func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {

    questionTextField.text = countryData[row]
    pickerView.hidden = true

}




// Resigns the keyboard if the user presses anywhere on the screen
override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {

    self.view.endEditing(true)
}


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

}

Answer 1

编辑:

在 viewDidLoad 或 viewWillAppear 中设置 myButton.userInteractionEnabled = false。

设置您的 textField 的 delegate。

然后

func textFieldDidBeginEditing(textField: UITextField) {
   if !textField.text.isEmpty
       myButton.enable = true

   } else {
       buttonLabel.enable = false
   }
}