xml非法字符过滤

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