Question

我找到了关于如何为UIAlertController 添加文本字段的示例代码，但我无法限制用户只输入10个字符作为限制< / strong>，当编辑为常规文本字段更改但无法检查UIAlertController上的文本字段时，我有一个删除最后一个字符的功能

//Function to Remove the last character func trimStr(existStr:String)->String{ var countExistTextChar = countElements(existStr) if countExistTextChar > 10 { var newStr = "" newStr = existStr.substringToIndex(advance(existStr.startIndex,(countExistTextChar-1))) return newStr }else{ return existStr } } var inputTextField: UITextField? //Create the AlertController let actionSheetController: UIAlertController = UIAlertController(title: "Alert", message: "Swiftly Now! Choose an option!", preferredStyle: .Alert) //Create and add the Cancel action let cancelAction: UIAlertAction = UIAlertAction(title: "Cancel", style: .Cancel) { action -> Void in //Do some stuff } actionSheetController.addAction(cancelAction) //Create and an option action let nextAction: UIAlertAction = UIAlertAction(title: "Next", style: .Default) { action -> Void in } actionSheetController.addAction(nextAction) //Add a text field **actionSheetController.addTextFieldWithConfigurationHandler { textField -> Void in //TextField configuration textField.textColor = UIColor.blueColor() inputTextField = textField** } //Present the AlertController self.presentViewController(actionSheetController, animated: true, completion: nil)

谢谢。

Answer 1

您可以将警报控制器的文本字段的委托设置为例如，这里显示https://stackoverflow.com/a/24852979/1187415：

actionSheetController.addTextFieldWithConfigurationHandler { [weak self] textField -> Void in
    //TextField configuration
    textField.textColor = UIColor.blueColor()
    textField.delegate = self
}

请注意，您必须将UITextFieldDelegate协议添加到您的帐户中查看控制器定义以进行编译：

class ViewController: UIViewController, UITextFieldDelegate {
    // ...

然后实现shouldChangeCharactersInRange委托方法，每当文本即将被更改时调用用户互动。它可以返回true或false以允许改变或否认它。

如何限制文本字段长度有各种示例这个委托方法，这是一个可能的实现：

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange,
    replacementString string: String) -> Bool {
        let newString = (textField.text as NSString).stringByReplacingCharactersInRange(range, withString: string) as NSString
        return newString.length <= 10
}

如果输入会导致文本字段，则会导致忽略输入长度大于10.或者你总是可以截断输入为10个字符：

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange,
    replacementString string: String) -> Bool {
        let newString = (textField.text as NSString).stringByReplacingCharactersInRange(range, withString: string)
        textField.text = trimStr(newString)
        return false
}

第二种方法的缺点是光标总是跳跃到文本字段的末尾，即使文本插入某处介于两者之间。

当用户使用swift键入时，限制UIAlertController中文本字段的输入？

1 个答案: