我试图检查当一个文本字段发生变化时，等效于textView - textViewDidChange的函数，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
}
}
哪种类型的工作，但topRightButton一经文本字段被按下就被启用，我想它只在文本实际输入时才被启用?
当前回答
到目前为止我处理它的方式:在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
}
其他回答
斯威夫特4.2
把这个写在viewDidLoad中
// to detect if TextField changed
TextField.addTarget(self, action: #selector(textFieldDidChange(_:)),
for: UIControl.Event.editingChanged)
把这个写在viewDidLoad外面
@objc func textFieldDidChange(_ textField: UITextField) {
// do something
}
你可以通过uicontrol。event。editingdidbegin改变事件或者任何你想检测的东西。
斯威夫特4
textField.addTarget(self, action: #selector(textIsChanging), for: UIControlEvents.editingChanged)
@objc func textIsChanging(_ textField:UITextField) {
print ("TextField is changing")
}
如果你想在用户完全输入后进行更改(一旦用户退出键盘或按enter键，它将被调用)。
textField.addTarget(self, action: #selector(textDidChange), for: UIControlEvents.editingDidEnd)
@objc func textDidChange(_ textField:UITextField) {
print ("TextField did changed")
}
斯威夫特
斯威夫特4.2
textfield.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)), for: .editingChanged)
and
@objc func textFieldDidChange(_ textField: UITextField) {
}
SWIFT 3和SWIFT 4.1
textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)), for: .editingChanged)
and
func textFieldDidChange(_ textField: UITextField) {
}
斯威夫特2.2
textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)), forControlEvents: UIControlEvents.EditingChanged)
and
func textFieldDidChange(textField: UITextField) {
//your code
}
objective - c
[textField addTarget:self action:@selector(textFieldDidChange:) forControlEvents:UIControlEventEditingChanged];
和textFieldDidChange方法是
-(void)textFieldDidChange :(UITextField *) textField{
//your code
}
如果不可能将addTarget绑定到你的UITextField，我建议你像上面建议的那样绑定其中一个，并在shouldChangeCharactersIn方法的末尾插入执行代码。
nameTextField.addTarget(self, action: #selector(RegistrationViewController.textFieldDidChange(_:)), for: .editingChanged)
@objc func textFieldDidChange(_ textField: UITextField) {
if phoneNumberTextField.text!.count == 17 && nameTextField.text!.count > 0 {
continueButtonOutlet.backgroundColor = UIColor(.green)
} else {
continueButtonOutlet.backgroundColor = .systemGray
}
}
在调用中shouldChangeCharactersIn func。
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
guard let text = textField.text else {
return true
}
let lastText = (text as NSString).replacingCharacters(in: range, with: string) as String
if phoneNumberTextField == textField {
textField.text = lastText.format("+7(NNN)-NNN-NN-NN", oldString: text)
textFieldDidChange(phoneNumberTextField)
return false
}
return true
}
你可以从UITextFieldDelegate中使用这个委托方法。它会随着角色的变化而爆发。
(Objective C) textField:shouldChangeCharactersInRange:replacementString:
(Swift) textField(_:shouldChangeCharactersInRange:replacementString:)
然而，这只会在更改之前触发(实际上，只有当你从这里返回true时，才会发生更改)。
