如何永久地显示从UITextField输入的数据到标签？

Question

我正在尝试创建一个函数,当用户在UITextField中输入文本时,标签显示输入的文本.

我该怎么做？

喜欢:

---

textField.text = "10"

Label.text = "\(textField.text) smthg" //. (10 smthg)

---

textField.text = "10.56"

Label.text = "\(textField.text) smthg" //. (10.56 smthg)

Answer 1

实现UITextFieldDelegate并将其设置为textField.delegate属性.从UITextFieldDelegate实现shouldChangeCharactersIn每次用户尝试更改文本字段中的输入时调用的回调方法:

class MyViewController: UIViewController {

    ...

    func viewDidLoad() {
        super.viewDidLoad()

        // set the textField's delegate to self
        textField.delegate = self
    }

}

extension MyViewController: UITextFieldDelegate {
    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        // to be always updated, you cannot use textField.text directly, because after this method gets called, the textField.text will be changed
        let newStringInTextField = (textField.text as NSString?)?.replacingCharacters(in: range, with: string)
        yourLabel.text = "\(newStringInTextField) smthg"
        return true
    }
}

使用函数的参数,您可以获得一个将出现的字符串,textField您可以将其设置为文本yourLabel.