为文本字段创建观察者以启用/禁用按钮时发生错误（Swift 3，Xcode 8.x）

Question

I am trying to create an observer for when the specified text field ends editing in order to disable/enable a button that forwards to a new segue.

In the end, I want to have a button that is only enabled when the the textfield is full and finished editing, which will allow it to move on to the next VC.

The error that is showing is:

 Cannot call value of non-function type '((UITextFieldDelegate) -> (UITextField) -> Bool)?'

Here's my source code:

import UIKit

class EmailViewController: UIViewController, UITextFieldDelegate {

// Back Button Two

@IBOutlet weak var backButtonTwo: UIButton!

// Email Header

@IBOutlet weak var emailSloganLabel: UILabel!

@IBOutlet weak var emailDescSloganLabel: UILabel!

// Email Form Entries

@IBOutlet weak var emailAddressMiniHeader: UILabel!

@IBOutlet weak var emailAddressTextField: UITextField!

@IBOutlet weak var emailAddressLineBreak: UILabel!

// Bottom Bar 'Next' Navigation

@IBOutlet weak var bottomNextButtonTwo: UIButton!

@IBOutlet weak var bottomNextLineBreakTwo: UILabel!




override func viewDidLoad() {
    super.viewDidLoad()

    emailAddressTextField.delegate = self

    emailAddressTextField.addTarget(self, action:  #selector(UITextFieldDelegate.textFieldShouldEndEditing("textFieldDidChange:")), for: UIControlEvents.editingChanged)

}


internal func textFieldShouldEndEditing(_ emailAddressTextField: UITextField) -> Bool {  if self.emailAddressTextField.text == "" {
    self.bottomNextButtonTwo.isEnabled = false
} else {
    self.bottomNextButtonTwo.isEnabled = true
    }
    return true
}


override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()

}


// Hide keyboard when user touches the outside keyboard


  override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
self.view.endEditing(true)
 }


// Hides keyboard when user pressed the 'Return' Key

func textFieldShouldReturn(_ textField: UITextField) -> Bool {
    emailAddressTextField.resignFirstResponder()
    return (true)

}

}

Thank you for any help, I truly appreciate it.

Answer 1

您应该删除addTarget因为它会与UITextFieldDelegate的textFieldShouldEndEditing发生冲突，并应直接使用它来知道文本字段何时完成编辑