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