ios - 检查 UIAlertController 中的字段验证

Question

我有带有输入字段的UIAlertController。我想检查该字段是否不为空以及字段文本是否为数字。但我不明白如何在警报窗口中显示验证消息。

var inputTextField: UITextField?

        let actionSheetController: UIAlertController = UIAlertController(title: "Enter price", message: "", preferredStyle: .Alert)

        let nextAction: UIAlertAction = UIAlertAction(title: "Continiue", style: .Default) { action -> Void in
            let priceField = actionSheetController.textFields![0] as UITextField
            if let userPrice = priceField.text {
                if userPrice == "" {
                    //RETURN AND SHOW SHOW ERROR MESSAGE, BUT KEEP ALERT OPEN
                }
}
}
        actionSheetController.addAction(nextAction)

        actionSheetController.addTextFieldWithConfigurationHandler { textField -> Void in
            inputTextField = textField
            inputTextField!.placeholder = "Product price"
        }
        self.presentViewController(actionSheetController, animated: true, completion: nil)

Answer 1

检查字符串是否为十进制数:

let nonDigits = NSCharacterSet.decimalDigitCharacterSet().invertedSet
let isValidNumber : Bool = priceField.text?.rangeOfCharacterFromSet(nonDigits) == nil