需要 UITextField 取 5 位数字 [英] Require a UITextField to take 5 digits

问题描述

我设置了一个 UITextField 来显示数字键盘.我如何要求用户准确输入 5 位数字?

I have a UITextField set up to show a number pad. How do I require the user to enter exactly 5 digits?

我四处看了看，发现我应该使用 shouldChangeCharactersInRange 但我不太明白如何实现它.

I poked around and saw I should use shouldChangeCharactersInRange but I'm not quite understanding how to implement that.

推荐答案

我只会在用户离开文本字段/使用按钮验证时使用它

I'd just use this when the user leaves the textfield/validates with a button

if ([myTextField.text length] != 5){

//Show alert or some other warning, like a red text

}else{
 //Authorized text, proceed with whatever you are doing
}

现在，如果您想在用户输入时计算字符数，您可以在 viewDidLoad

Now if you want to count the chars WHILE the user is typing, you might use in viewDidLoad

[myTextfield addTarget: self action@selector(textfieldDidChange:) forControlEvents:UIControlEventsEditingChanged]

-(void)textFieldDidChange:(UITextField*)theTextField{
 //This happens every time the textfield changes
}

如果您需要更多帮助，请务必在评论中提出问题:)

Please make sure to ask questions in the comments if you need more help :)

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