在实时输入字符时，如何获取 UITextfield 的值？

Question

我正在尝试实时调节 UITextfield 的输入，这意味着在用户输入时。我有这个字符集，我需要将其与输入字符串进行比较，并且在编辑时如果输入了未经授权的字符，我想传递警报。这是我的字符集：

let acceptedChars = NSCharacterSet(charactersInString: "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890_")

现在如何实时捕获特定文本字段并跟踪其输入？

Answer 1

var strings: NSString?

class ViewController: UIViewController,UITextFieldDelegate //设置你的文本框委托

 func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool
{  if(textField .isEqual(your textfield))
    {
    strings=string;
    let acceptedChars = NSCharacterSet(charactersInString: "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890_").invertedSet;

     if (strings!.rangeOfCharacterFromSet(acceptedChars.invertedSet).location != NSNotFound)
    {
        return true;
    }
    else
    {
        return false;
    }        
}
else
{
return true;
}
}

Answer 2

使用下面的方法

   func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool
    {
        if textField.isEqual(<textField whose value to be copied>)
        {
            <TextField to be updated>.text = (textField.text as NSString).stringByReplacingCharactersInRange(range, withString: string)
        }
    
        return true
    }

Answer 3

试试这个：

 func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
        let invalidCharacters = NSCharacterSet(charactersInString: "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890_").invertedSet
        if let range = string.rangeOfCharacterFromSet(invalidCharacters, options: nil, range:Range<String.Index>(start: string.startIndex, end: string.endIndex)) {
            return false
        }

        return true
    }

Answer 4

您可以像这样为值更改事件注册您的 textField

textfield.addTarget(self, action:"textFieldDidChange", forControlEvents:UIControlEvents.EditingChanged)

func textFieldDidChange(){
    // put your code
}

它将对您实时输入的每个字符起作用

Answer 5

一种简单的委托方法，而且确实更有效：

func textFieldDidChangeSelection(_ textField: UITextField) {
    print(textField.text)
}

在实时输入字符时，如何获取 UITextfield 的值？

How do I get the value of a UITextfield as characters are being typed in real time?

xcode

alert

uitextfield

ios

swift

使用下面的方法