xml非法字符过滤

NSString+XMLInvalidateCharactersEscaper.h

#import <Foundation/Foundation.h>

@interface NSString (XMLInvalidateCharactersEscaper)

/**
 * 
 +------------+------------+------------+
 |   禁用字符  |  转义字符  |    说明     |
 +------------+------------+------------+
 |     <      |   &lt;     |    小于     |
 |     >      |   &gt;		 |    大于     |
 |     &      |   &amp;    |    和       |
 |     '      |   &apos;   |    单引号   |
 |     "      |   &quot;   |    双引号   |
 +------------+------------+------------+
 *
 * 转义字符对照表
 */
@property (nonatomic, strong) NSDictionary *escapeCharacterLUT;


/**
 * 对XML双引号内非法的XML执行转义
 */
///////////////////////////////////////////////////////////////////////////////////////////////////
- (NSString *)escapeInvalideCharactersInXML;

@end

NSString+XMLInvalidateCharactersEscaper.m

#import "NSString+XMLInvalidateCharactersEscaper.h"
#import <objc/runtime.h>
 
static void *CustomObjectKey;
 
@implementation NSString (XMLInvalidateCharactersEscaper)
 
/*
 * category中使用property的示例
 */
///////////////////////////////////////////////////////////////////////////////////////////////////
- (NSDictionary *)escapeCharacterLUT {
  NSDictionary *result = objc_getAssociatedObject(self, &CustomObjectKey);
  if (!result) {
    result = @{@"<"  : @"&lt;",
               @">"  : @"&gt;",
               @"&"  : @"&amp;",
               @"'"  : @"&apos;",
               @"\"" : @"&quot;"};
    
    objc_setAssociatedObject(self, &CustomObjectKey, result, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
  }
  
  return result;
}
 
 
///////////////////////////////////////////////////////////////////////////////////////////////////
- (void)setEscapeCharacterLUT:(id)newObject {
  objc_setAssociatedObject(self, CustomObjectKey, newObject, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
 
 
///////////////////////////////////////////////////////////////////////////////////////////////////
- (NSString *)escapeInvalideCharactersInXML {
  return [self escapeInvalideCharacterWithRegex:[[self.escapeCharacterLUT allKeys] componentsJoinedByString:@"|"]];
}
 
 
/**
 * 将匹配实例中的非法字符过滤掉
 */
///////////////////////////////////////////////////////////////////////////////////////////////////
- (NSString *)escapeInvalideCharacterWithRegex:(NSString *)patten{
  NSError* error = NULL;
  NSMutableString *mutableString = [self mutableCopy];
  
  NSRegularExpression* regex = [NSRegularExpression regularExpressionWithPattern:patten
                                                                         options:NSRegularExpressionCaseInsensitive
                                                                           error:&error];
  NSInteger offset = 0;
  for (NSTextCheckingResult* result in [regex matchesInString:mutableString options:0 range:NSMakeRange(0, [self length])]) {
    NSRange resultRange = [result rangeAtIndex:0];
    resultRange.location += offset;
    NSString* matchString = [mutableString substringWithRange:resultRange];
    NSString* replacement = self.escapeCharacterLUT[matchString];
    
    [mutableString replaceCharactersInRange:resultRange withString:replacement];
    offset += ([replacement length] - [matchString length]);
  }
  
  return [mutableString copy];
}
 
@end