仅允许UITextField使用字母数字字符 [英] Allow only alphanumeric characters for a UITextField

问题描述

如何在iOS UITextField 中仅允许输入字母数字字符？

How would I go about allowing inputting only alphanumeric characters in an iOS UITextField?

推荐答案

使用UITextFieldDelegate方法 -textField：shouldChangeCharactersInRange：replacementString：，其中NSCharacterSet包含您要允许的字符的反转。例如：

Use the UITextFieldDelegate method -textField:shouldChangeCharactersInRange:replacementString: with an NSCharacterSet containing the inverse of the characters you want to allow. For example:

// in -init, -initWithNibName:bundle:, or similar
NSCharacterSet *blockedCharacters = [[[NSCharacterSet alphanumericCharacterSet] invertedSet] retain];

- (BOOL)textField:(UITextField *)field shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)characters
{
    return ([characters rangeOfCharacterFromSet:blockedCharacters].location == NSNotFound);
}

// in -dealloc
[blockedCharacters release];

请注意，您需要声明您的类实现了协议（即 @interface MyClass：SomeSuperclass< UITextFieldDelegate> ）并将文本字段的委托设置为您班级的实例。

Note that you’ll need to declare that your class implements the protocol (i.e. @interface MyClass : SomeSuperclass <UITextFieldDelegate>) and set the text field’s delegate to the instance of your class.

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