Iphone UITextField值已更改事件？

如何使文本字段的内容发生变化时调用函数？

Objective-C

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

Swift 4

myTextField.addTarget(self, action: #selector(textFieldDidChange(sender:)), for: .editingChanged)

@objc func textFieldDidChange(sender: UITextField) {...}

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

@objc func textFieldDidChange(sender: UITextField){
   print("textFieldDidChange is called")
}

---

实际上，

UITextField

没有值更改事件，使用

UIControlEventEditingChanged

我解决了更改shouldChangeChractersInRange行为的问题。如果您返回否，iOS将不会在内部应用更改，相反，您有机会手动更改并在更改后执行任何操作

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    //Replace the string manually in the textbox
    textField.text = [textField.text stringByReplacingCharactersInRange:range withString:string];
    //perform any logic here now that you are sure the textbox text has changed
    [self didChangeTextInTextField:textField];
    return NO; //this make iOS not to perform any action
}

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对斯威夫特来说，这很方便-

textField.addTarget(self, action: #selector(onTextChange), forControlEvents: UIControlEvents.EditingChanged)

这是我的解决方案

Swift 4

myTextField.addTarget(self, action: #selector(textFieldDidChange(sender:)), for: .editingChanged)

@objc func textFieldDidChange(sender: UITextField) {...}

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

@objc func textFieldDidChange(sender: UITextField){
   print("textFieldDidChange is called")
}

---

奇怪的是，基于UIControlEventDidEnd和UIControlEventDidBegin，人们会假设它是UIControlEventValueChanged。。。UIControlEventValueChanged到底做了什么？@kovpas如果我们以编程方式更改值，那么它就不会得到调用，知道该做什么吗？。例如，myTextField.text=“Krishna”请注意，设置文本属性会将光标移动到文本的末尾，这可能会影响编辑您可以自己处理它