iOS中的Regex将文本字段限制为仅包含字母和单撇号

您可以这样做,但如果输入无效,则需要显示错误。

- (BOOL)textFieldShouldEndEditing:(UITextField *)aTextField
{
    NSString *const regularExpression = @"^[a-zA-Z']+$";
    NSError *error = NULL;
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:regularExpression
                                                                           options:kNilOptions
                                                                             error:&error];
    if (error) {
        // Handle error
    }

    NSUInteger numberOfMatches = [regex numberOfMatchesInString:aString
                                                        options:0
                                                          range:NSMakeRange(0, [aString length])];
    return numberOfMatches > 0;
}

regx应为

EFGHIJKLMNOPQRSTUVWXYZabcdefghijlmnopqrstuvxyz'

你可以使用

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{

        if (textField == emailid) {
            NSCharacterSet *cs = [[NSCharacterSet characterSetWithCharactersInString:@"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'"] invertedSet];
            NSString *filtered = [[string componentsSeparatedByCharactersInSet:cs] componentsJoinedByString:@""];
            ;
            return [string isEqualToString:filtered];
        }
    }

您可以使用检查是否应插入输入的函数,并限制其中的字符。由于您的限制相当简单,因此不需要正则表达式,您可以使用字符集。

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{

    NSMutableCharacterSet *allowedCharacters = [NSMutableCharacterSet alphanumericCharacterSet];
    [allowedCharacters addCharactersInString:@"'"];

    if([string rangeOfCharacterFromSet:allowedCharacters.invertedSet].location == NSNotFound){
        return YES;
    }

    return NO;
}