ios - 如果文本字段为空，如何禁用按钮？

Question

如果文本字段中没有任何内容，我将尝试禁用继续按钮。 这是我的代码...

import UIKit

class ViewController: UIViewController, UITextFieldDelegate {

@IBOutlet weak var nounTextField: UITextField!
@IBOutlet weak var `continue`: UIButton!

var noun = String()

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

@IBAction func continueButton(sender: AnyObject) {
    noun = nounTextField.text!
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    let nvc = segue.destinationViewController as! ViewController2
    nvc.noun2 = noun
} 
}

Answer 1

因为你已经让你的类成为一个 UITextFieldDelegate 广告

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {

    let text = (textField.text as NSString).stringByReplacingCharactersInRange(range, withString: string)

    if !text.isEmpty{
        continueButton.userInteractionEnabled = true 
    } else {
        continueButton.userInteractionEnabled = false 
    } 
    return true
}

同时更新你的 viewDidLoad 函数

override func viewDidLoad() {
    super.viewDidLoad()

    nounTextField.delegate = self
    if nounTextField.text.isEmpty{
        continueButton.userInteractionEnabled = false 
    }
}