Swift 3.0.1+(其他一些Swift 3.0的答案不是最新的)

textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)),
                          for: UIControlEvents.editingChanged)

func textFieldDidChange(_ textField: UITextField) {

}

你应该遵循以下步骤:

对文本框进行Outlet引用 AssignUITextFieldDelegate给控制器类 配置yourTextField.delegate 实现你需要的任何函数

示例代码:

import UIKit

class ViewController: UIViewController, UITextFieldDelegate {

    @IBOutlet var yourTextFiled : UITextField!

    override func viewDidLoad() {
        super.viewDidLoad()

        yourTextFiled.delegate = self
    }


    func textFieldDidEndEditing(_ textField: UITextField) {
        // your code
    }

    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        // your code
    }

    .
    .
    .
}

Swift 3.0.1+(其他一些Swift 3.0的答案不是最新的)

textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)),
                          for: UIControlEvents.editingChanged)

func textFieldDidChange(_ textField: UITextField) {

}

斯威夫特4

在viewDidLoad ():

    //ADD BUTTON TO DISMISS KEYBOARD

    // Init a keyboard toolbar 
    let toolbar = UIView(frame: CGRect(x: 0, y: view.frame.size.height+44, width: view.frame.size.width, height: 44))
    toolbar.backgroundColor = UIColor.clear

    // Add done button
    let doneButt = UIButton(frame: CGRect(x: toolbar.frame.size.width - 60, y: 0, width: 44, height: 44))
    doneButt.setTitle("Done", for: .normal)
    doneButt.setTitleColor(MAIN_COLOR, for: .normal)
    doneButt.titleLabel?.font = UIFont(name: "Titillium-Semibold", size: 13)
    doneButt.addTarget(self, action: #selector(dismissKeyboard), for: .touchUpInside)
    toolbar.addSubview(doneButt)

    USDTextField.inputAccessoryView = toolbar

增加这个函数:

    @objc func dismissKeyboard() {
      //Causes the view (or one of its embedded text fields) to resign the first responder status.
      view.endEditing(true)
    }

你可以通过“shouldchangecharter”委托或者“begin and end”文本字段委托来管理编辑。别忘了设置委托

我设法做到这一点使用“did开始和结束编辑”下面。

//MARK:- TextViewDelegate
extension ViewController: UITextFieldDelegate {
    func textFieldDidEndEditing(_ textField: UITextField) {
        let count = self.tfEmail.text?.count ?? 0
        if textField == self.tfEmail {
            if count == 0{
              //Empty textfield
            }else{
              //Non-Empty textfield
            }
        }
    }
    func textFieldDidBeginEditing(_ textField: UITextField) {
        if textField == self.tfEmail{
            //when user taps on textfield
        }
    }
}

textField(_:shouldChangeCharactersIn:replacementString:)在Xcode 8中为我工作，Swift 3如果你想检查每一个按键。

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

    // Whatever code you want to run here.
    // Keep in mind that the textfield hasn't yet been updated,
    // so use 'string' instead of 'textField.text' if you want to
    // access the string the textfield will have after a user presses a key

    var statusText = self.status.text
    var usernameText = self.username.text

    switch textField{
    case self.status:
        statusText = string
    case self.username:
        usernameText = string
    default:
        break
    }

    if statusText == "" && usernameText == "" {
        self.topRightButton.enabled = false
    } else {   
        self.topRightButton.enabled = true
    }

    //Return false if you don't want the textfield to be updated
    return true
}