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，到目前为止我已经做到了这一点：
func textFieldDidBeginEditing(textField: UITextField) {
if self.status.text == "" && self.username.text == "" {
self.topRightButton.enabled = false
} else {
self.topRightButton.enabled = true
}
}
这种方法可以工作，但是topRightButton会在用户点击文本框时立即启用，我希望它只有在实际输入文本时才启用。
SWIFT
Swift 4.2
textfield.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)), for: .editingChanged)
和
@objc func textFieldDidChange(_ textField: UITextField) {
}
SWIFT 3 和 swift 4.1
textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)), for: .editingChanged)
和
func textFieldDidChange(_ textField: UITextField) {
}
SWIFT 2.2
textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)), forControlEvents: UIControlEvents.EditingChanged)
和
func textFieldDidChange(textField: UITextField) {
//your code
}
OBJECTIVE-C
[textField addTarget:self action:@selector(textFieldDidChange:) forControlEvents:UIControlEventEditingChanged];
textFieldDidChange方法是
-(void)textFieldDidChange :(UITextField *) textField{
//your code
}
你可以在界面构建器中进行这个连接。
在你的故事板中，点击屏幕顶部的助理编辑器（中间的两个圆圈）。
在界面构建器中，按住Ctrl键并单击文本框。
从EditingChanged拖动到助理视图中的视图控制器类内部。
给你的函数命名（例如"textDidChange"）并点击连接。
textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)),
for: .editingChanged)
并处理方法：
@objc func textFieldDidChange(_ textField: UITextField) {
}
textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)),
for: UIControlEvents.editingChanged)
并且处理方法：
@objc func textFieldDidChange(_ textField: UITextField) {
}
textField.addTarget(self, action: #selector(textFieldDidChange(textField:)), for: .editingChanged)
和处理方法:
func textFieldDidChange(textField: UITextField) {
}
UITextFieldDelegate中。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
}
Swift4 版本
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let updatedString = (textField.text as NSString?)?.replacingCharacters(in: range, with: string)
return true
}
Swift 3
textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(sender:)), for: UIControlEvents.editingChanged)
textField(_:shouldChangeCharactersIn:replacementString:) 在Xcode 8和Swift 3中对我很有用，如果您想检查每一个按键。
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
}
Swift 4
遵循 UITextFieldDelegate。
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 3.0.1+（其他一些Swift 3.0的答案已经过时）
textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)),
for: UIControlEvents.editingChanged)
func textFieldDidChange(_ textField: UITextField) {
}
(Objective C) textField:shouldChangeCharactersInRange:replacementString:
(Swift) textField(_:shouldChangeCharactersInRange:replacementString:)
然而，这只会在更改之前触发（确实，只有在从这里返回true时才会进行更改）。
.isEmpty方法直到此方法有机会返回true之后才等同于true；告诉应用程序文本字段应该更改。 - Levi Robertspod 'RxSwift', '~> 3.0'
pod 'RxCocoa', '~> 3.0'
显然添加导入
import RxSwift
import RxCocoa
所以您有一个textfield: UITextField
let observable: Observable<String?> = textField.rx.text.asObservable()
observable.subscribe(
onNext: {(string: String?) in
print(string!)
})
你还有其他三种方法..
viewDidLoad之前立即设置。操作是逐字相同的。应用程序在按下键盘按钮时立即崩溃。编辑：问题解决了！操作内缺少分号。我以为它只需要与函数名称相同。 - Levi Roberts