Ios UITextField更改时如何检查？

我正在尝试检查文本字段何时更改，相当于用于textView的函数-

textViewDidChange

到目前为止，我已经完成了以下操作：

  func textFieldDidBeginEditing(textField: UITextField) {
        if self.status.text == "" && self.username.text == "" {
            self.topRightButton.enabled = false
        } else {   
            self.topRightButton.enabled = true
        }
    }

哪种方式有效，但按下文本字段后，

topRightButton

将立即启用，我希望只有在实际键入文本时才启用它？

SWIFT

---

Swift 4.2

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

textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)), forControlEvents: UIControlEvents.EditingChanged)

及

SWIFT 3和SWIFT 4.1

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

及

SWIFT 2.2

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

textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)), forControlEvents: UIControlEvents.EditingChanged)

及

目标-C

[textField addTarget:self action:@selector(textFieldDidChange:) forControlEvents:UIControlEventEditingChanged];

而textFieldDidChange方法是

-(void)textFieldDidChange :(UITextField *) textField{
    //your code
}

SWIFT

---

Swift 4.2

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

textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)), forControlEvents: UIControlEvents.EditingChanged)

及

SWIFT 3和SWIFT 4.1

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

及

SWIFT 2.2

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

textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)), forControlEvents: UIControlEvents.EditingChanged)

及

目标-C

[textField addTarget:self action:@selector(textFieldDidChange:) forControlEvents:UIControlEventEditingChanged];

而textFieldDidChange方法是

-(void)textFieldDidChange :(UITextField *) textField{
    //your code
}

---

可以从UITextFieldDelegate使用此委托方法。它会随着角色的每一次变化而激发

(Objective C) textField:shouldChangeCharactersInRange:replacementString:
(Swift) textField(_:shouldChangeCharactersInRange:replacementString:)

---

但是，这仅在进行更改之前激发（实际上，只有在此处返回true时才会进行更改）。

您可以从UITextFieldDelegate使用此委托方法。它会随着角色的每一次变化而激发

(Objective C) textField:shouldChangeCharactersInRange:replacementString:
(Swift) textField(_:shouldChangeCharactersInRange:replacementString:)

---

但是，这只会在做出更改之前触发（实际上，只有从这里返回true时才会进行更改）。

到目前为止我处理它的方式：在

UITextFieldDelegate

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool
{
    // text hasn't changed yet, you have to compute the text AFTER the edit yourself
    let updatedString = (textField.text as NSString?)?.stringByReplacingCharactersInRange(range, withString: string)

    // do whatever you need with this updated string (your code)


    // always return true so that changes propagate
    return true
}

override func viewDidLoad() {
    super.viewDidLoad()

    textField.delegate = self

    textField.addTarget(self, action: #selector(UITextFieldDelegate.textFieldShouldEndEditing(_:)), for: UIControlEvents.editingChanged)
}

迅捷4版

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    let updatedString = (textField.text as NSString?)?.replacingCharacters(in: range, with: string)
    return true
}

---

到目前为止我的处理方式是：在

UITextFieldDelegate

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool
{
    // text hasn't changed yet, you have to compute the text AFTER the edit yourself
    let updatedString = (textField.text as NSString?)?.stringByReplacingCharactersInRange(range, withString: string)

    // do whatever you need with this updated string (your code)


    // always return true so that changes propagate
    return true
}

override func viewDidLoad() {
    super.viewDidLoad()

    textField.delegate = self

    textField.addTarget(self, action: #selector(UITextFieldDelegate.textFieldShouldEndEditing(_:)), for: UIControlEvents.editingChanged)
}

迅捷4版

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    let updatedString = (textField.text as NSString?)?.replacingCharacters(in: range, with: string)
    return true
}

---

您可以在interface builder中建立此连接

在情节提要中，单击屏幕顶部的助理编辑器（中间的两个圆圈）。

按住Ctrl键并单击interface builder中的文本字段

在助手视图中，从EditingChanged拖动到视图控制器类内部。

命名您的函数（例如“textdichange”），然后单击连接。

---

您可以在interface builder中建立此连接

在情节提要中，单击屏幕顶部的助理编辑器（中间的两个圆圈）。

按住Ctrl键并单击interface builder中的文本字段

在助手视图中，从EditingChanged拖动到视图控制器类内部。

命名您的函数（例如“textdichange”），然后单击连接。

斯威夫特3

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

斯威夫特3

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

---

这就是如何使用Swift 3添加

textField文本更改侦听器的方法：

将类声明为
UITextFieldDelegate

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool
{
    // text hasn't changed yet, you have to compute the text AFTER the edit yourself
    let updatedString = (textField.text as NSString?)?.stringByReplacingCharactersInRange(range, withString: string)

    // do whatever you need with this updated string (your code)


    // always return true so that changes propagate
    return true
}

override func viewDidLoad() {
    super.viewDidLoad()

    textField.delegate = self

    textField.addTarget(self, action: #selector(UITextFieldDelegate.textFieldShouldEndEditing(_:)), for: UIControlEvents.editingChanged)
}

然后只需添加textFieldShouldEndEditing函数：

func textFieldShouldEndEditing(_ textField: UITextField) -> Bool { // do stuff
        return true 
}

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

这就是如何使用Swift 3添加
textField文本更改侦听器的方法：

将类声明为
UITextFieldDelegate

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool
{
    // text hasn't changed yet, you have to compute the text AFTER the edit yourself
    let updatedString = (textField.text as NSString?)?.stringByReplacingCharactersInRange(range, withString: string)

    // do whatever you need with this updated string (your code)


    // always return true so that changes propagate
    return true
}

override func viewDidLoad() {
    super.viewDidLoad()

    textField.delegate = self

    textField.addTarget(self, action: #selector(UITextFieldDelegate.textFieldShouldEndEditing(_:)), for: UIControlEvents.editingChanged)
}

然后只需添加textFieldShouldEndEditing函数：

func textFieldShouldEndEditing(_ textField: UITextField) -> Bool { // do stuff
        return true 
}

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

在Xcode 8，Swift 3中为我工作，如果你想检查每一次按键

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
}

在Xcode 8，Swift 3中为我工作，如果你想检查每一次按键

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
}

Swift 5.0
处理方法：

@objc func textFieldDidChange(_ textField: UITextField) {

}

@objc func textFieldDidChange(_ textField: UITextField) {

}

func textFieldDidChange(textField: UITextField) { 

}

Swift 4.0
处理方法：

@objc func textFieldDidChange(_ textField: UITextField) {

}

@objc func textFieldDidChange(_ textField: UITextField) {

}

func textFieldDidChange(textField: UITextField) { 

}

Swift 3.0
处理方法：

@objc func textFieldDidChange(_ textField: UITextField) {

}

@objc func textFieldDidChange(_ textField: UITextField) {

}

func textFieldDidChange(textField: UITextField) { 

}

Swift 5.0
处理方法：

@objc func textFieldDidChange(_ textField: UITextField) {

}

@objc func textFieldDidChange(_ textField: UITextField) {

}

func textFieldDidChange(textField: UITextField) { 

}

Swift 4.0
处理方法：

@objc func textFieldDidChange(_ textField: UITextField) {

}

@objc func textFieldDidChange(_ textField: UITextField) {

}

func textFieldDidChange(textField: UITextField) { 

}

Swift 3.0
处理方法：

@objc func textFieldDidChange(_ textField: UITextField) {

}

@objc func textFieldDidChange(_ textField: UITextField) {

}

func textFieldDidChange(textField: UITextField) { 

}

Swift 3.0.1+（其他一些Swift 3.0答案不是最新的）

Swift 3.0.1+（其他一些Swift 3.0答案不是最新的）

可能使用RxSwift？

需要

明显增加进口

import RxSwift
import RxCocoa

所以你有一个
textfield:UITextField

let observable: Observable<String?> = textField.rx.text.asObservable()
observable.subscribe(
            onNext: {(string: String?) in
                print(string!)
        })

let observable:observable=textField.rx.text.asObservable（）
可观察的(
onNext:{（字符串：字符串？）在
打印（字符串！）
})

你还有其他3种方法

一个错误
未完成
onDisposed
onNext
可能使用RxSwift？

需要

明显增加进口

import RxSwift
import RxCocoa

所以你有一个
textfield:UITextField

let observable: Observable<String?> = textField.rx.text.asObservable()
observable.subscribe(
            onNext: {(string: String?) in
                print(string!)
        })

let observable:observable=textField.rx.text.asObservable（）
可观察的(
onNext:{（字符串：字符串？）在
打印（字符串！）
})

你还有其他3种方法

一个错误
未完成
onDisposed
onNext
swift 4

textField.addTarget(self, action: #selector(textIsChanging), for: UIControlEvents.editingChanged)

@objc func textIsChanging(_ textField:UITextField) {

 print ("TextField is changing")

}

在viewDidLoad（）中：

添加此功能：

func textFieldShouldEndEditing(_ textField: UITextField) -> Bool { // do stuff
        return true 
}

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

swift 4

textField.addTarget(self, action: #selector(textIsChanging), for: UIControlEvents.editingChanged)

@objc func textIsChanging(_ textField:UITextField) {

 print ("TextField is changing")

}

在viewDidLoad（）中：

添加此功能：

func textFieldShouldEndEditing(_ textField: UITextField) -> Bool { // do stuff
        return true 
}

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

Swift 4

textField.addTarget(self, action: #selector(textIsChanging), for: UIControlEvents.editingChanged)

@objc func textIsChanging(_ textField:UITextField) {

 print ("TextField is changing")

}

符合UITextFieldDelegate的要求

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    // figure out what the new string will be after the pending edit
    let updatedString = (textField.text as NSString?)?.replacingCharacters(in: range, with: string)

    // Do whatever you want here


    // Return true so that the change happens
    return true
}

Swift 4

textField.addTarget(self, action: #selector(textIsChanging), for: UIControlEvents.editingChanged)

@objc func textIsChanging(_ textField:UITextField) {

 print ("TextField is changing")

}

符合UITextFieldDelegate的要求

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    // figure out what the new string will be after the pending edit
    let updatedString = (textField.text as NSString?)?.replacingCharacters(in: range, with: string)

    // Do whatever you want here


    // Return true so that the change happens
    return true
}

Swift 4

textField.addTarget(self, action: #selector(textIsChanging), for: UIControlEvents.editingChanged)

@objc func textIsChanging(_ textField:UITextField) {

 print ("TextField is changing")

}

如果您希望在用户完全输入后进行更改（一旦用户关闭键盘或按enter键，将调用该更改）

Swift 4

textField.addTarget(self, action: #selector(textIsChanging), for: UIControlEvents.editingChanged)

@objc func textIsChanging(_ textField:UITextField) {

 print ("TextField is changing")

}

如果您希望在用户完全输入后进行更改（一旦用户关闭键盘或按enter键，将调用该更改）

您应该遵循以下步骤：

对文本字段进行出口引用
将AssignUITextFieldDelegate分配给控制器类
配置yourTextField.delegate
实现您需要的任何功能
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
    }

    .
    .
    .
}

您应该遵循以下步骤：

对文本字段进行出口引用
将AssignUITextFieldDelegate分配给控制器类
配置yourTextField.delegate
实现您需要的任何功能
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 4.2

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

textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)), forControlEvents: UIControlEvents.EditingChanged)

在viewDidLoad中编写此代码

// to detect if TextField changed
TextField.addTarget(self, action: #selector(textFieldDidChange(_:)),
                                   for: UIControl.Event.editingChanged)

@objc func textFieldDidChange(_ textField: UITextField) {
    // do something
}

在viewDidLoad外部编写此文件

// to detect if TextField changed
TextField.addTarget(self, action: #selector(textFieldDidChange(_:)),
                                   for: UIControl.Event.editingChanged)

@objc func textFieldDidChange(_ textField: UITextField) {
    // do something
}

您可以通过UIControl.event.editingdidbeagin或任何您想要检测的内容来更改事件。
Swift 4.2

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

textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)), forControlEvents: UIControlEvents.EditingChanged)

在viewDidLoad中编写此代码

// to detect if TextField changed
TextField.addTarget(self, action: #selector(textFieldDidChange(_:)),
                                   for: UIControl.Event.editingChanged)

@objc func textFieldDidChange(_ textField: UITextField) {
    // do something
}

在viewDidLoad外部编写此文件

// to detect if TextField changed
TextField.addTarget(self, action: #selector(textFieldDidChange(_:)),
                                   for: UIControl.Event.editingChanged)

@objc func textFieldDidChange(_ textField: UITextField) {
    // do something
}

你可以改变主意