限制UITextField中的字符数 [英] Restrict the number of characters in UITextField

问题描述

我看到了很多答案，但似乎没有一个有效. 我有一个带有两个UITextField的以编程方式创建的UIAlertView. 我想限制字符数:

I've seen a lot of answers, but it seems that none of them has worked. I have a programmatically created UIAlertView with two UITextFields. I want to restrict the number of characters :

• 第一个字段中的12个字符
• 第二个字段中有1个字符

第一个域代码:

alertDialog.addTextField { (nameField) in
        nameField.placeholder = "Name"
        nameField.borderStyle = .roundedRect
        nameField.clearButtonMode = .whileEditing
        }

第二

alertDialog.addTextField { (keyField) in
        keyField.placeholder = "Key"
        keyField.borderStyle = .roundedRect
        keyField.clearButtonMode = .whileEditing

    }

如何正确限制数量(假设这些字段中没有粘贴)

How can I correctly restrict the number (Let's pretend that there will be no paste in these field)

推荐答案

将textField委托设置为相应的类(在我的情况下，自身是ViewController)

Set textField delegates to respective class (in my case self is ViewController)

nameField.delegate = self
keyField.delegate = self

然后您可以通过以下方式限制字符

Then you can restrict characters by

extension ViewController : UITextFieldDelegate {

    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {

        switch textField {
        case nameField:
            if ((textField.text?.length)! + (string.length - range.length)) > 12 {
                return false
            }

        case keyField:
            if ((textField.text?.length)! + (string.length - range.length)) > 1 {
                return false
            }
        }
        return true 
    }
}

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