NSCharacterSet：如何添加“_” to alphanumericCharacterSet文本限制？ [英] NSCharacterSet: How do I add "_" to alphanumericCharacterSet text restriction?

问题描述

构建NSCharacter集以限制UITextField以输入用户名。我希望用户能够输入下划线（所以[A-Za-z0-9_]），但alphanumericCharacterSet不包含它。有没有办法在短格式中指定类似的范围？我看到 +（id）characterSetWithRange：（NSRange）aRange ，但我真的不明白它是如何工作的。

Building an NSCharacter set to restrict a UITextField for entering user names. I want the user to be able to also enter an underscore (so [A-Za-z0-9_]) but alphanumericCharacterSet does not include it. Is there a way to specify a range like that in short form? I see + (id)characterSetWithRange:(NSRange)aRange, but I'm not really understanding how that would work.

我有一个简单的UITextField子类，我将字符集传递给。限制工作正常，不允许用户输入除字母数字之外的任何内容。只需要在这些限额中添加_。

I've got a simple UITextField sub-class that I pass the character set to. The restriction works fine and doesn't allow the user to enter anything but alpha numeric. Just need to add the "_" to those allowances.

NSCharacterSet *characterSet = [NSCharacterSet alphanumericCharacterSet];
[textField setAllowed:characterSet];
[textField setFrame:frame];

推荐答案

Objective-C

NSMutableCharacterSet *_alnum = [NSMutableCharacterSet characterSetWithCharactersInString:@"_"];
[_alnum formUnionWithCharacterSet:[NSCharacterSet alphanumericCharacterSet]];

Swift

let _alnum = NSMutableCharacterSet(charactersIn: "_")
_alnum.formUnion(with: .alphanumerics)

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