问Objective-C / Cocoa Touch中的HTML字符解码

EN

- (NSString *)stringByConvertingHTMLToPlainText;
- (NSString *)stringByDecodingHTMLEntities;
- (NSString *)stringByEncodingHTMLEntities;
- (NSString *)stringWithNewLinesAsBRs;
- (NSString *)stringByRemovingNewLinesAndWhitespace;

/// Get a string where internal characters that are escaped for HTML are unescaped 
//
///  For example, '&' becomes '&'
///  Handles   and 2 cases as well
///
//  Returns:
//    Autoreleased NSString
//
- (NSString *)gtm_stringByUnescapingFromHTML;

- (NSString *)stringByDecodingXMLEntities {
    NSUInteger myLength = [self length];
    NSUInteger ampIndex = [self rangeOfString:@"&" options:NSLiteralSearch].location;

    // Short-circuit if there are no ampersands.
    if (ampIndex == NSNotFound) {
        return self;
    }
    // Make result string with some extra capacity.
    NSMutableString *result = [NSMutableString stringWithCapacity:(myLength * 1.25)];

    // First iteration doesn't need to scan to & since we did that already, but for code simplicity's sake we'll do it again with the scanner.
    NSScanner *scanner = [NSScanner scannerWithString:self];
    do {
        // Scan up to the next entity or the end of the string.
        NSString *nonEntityString;
        if ([scanner scanUpToString:@"&" intoString:&nonEntityString]) {
            [result appendString:nonEntityString];
        }
        if ([scanner isAtEnd]) {
            goto finish;
        }
        // Scan either a HTML or numeric character entity reference.
        if ([scanner scanString:@"&" intoString:NULL])
            [result appendString:@"&"];
        else if ([scanner scanString:@"'" intoString:NULL])
            [result appendString:@"'"];
        else if ([scanner scanString:@""" intoString:NULL])
            [result appendString:@"\""];
        else if ([scanner scanString:@"<" intoString:NULL])
            [result appendString:@"<"];
        else if ([scanner scanString:@"&gt;" intoString:NULL])
            [result appendString:@">"];
        else if ([scanner scanString:@"&#" intoString:NULL]) {
            BOOL gotNumber;
            unsigned charCode;
            NSString *xForHex = @"";

            // Is it hex or decimal?
            if ([scanner scanString:@"x" intoString:&xForHex]) {
                gotNumber = [scanner scanHexInt:&charCode];
            }
            else {
                gotNumber = [scanner scanInt:(int*)&charCode];
            }
            if (gotNumber) {
                [result appendFormat:@"%C", charCode];
            }
            else {
                NSString *unknownEntity = @"";
                [scanner scanUpToString:@";" intoString:&unknownEntity];
                [result appendFormat:@"&#%@%@;", xForHex, unknownEntity];
                NSLog(@"Expected numeric character entity but got &#%@%@;", xForHex, unknownEntity);
            }
            [scanner scanString:@";" intoString:NULL];
        }
        else {
            NSString *unknownEntity = @"";
            [scanner scanUpToString:@";" intoString:&unknownEntity];
            NSString *semicolon = @"";
            [scanner scanString:@";" intoString:&semicolon];
            [result appendFormat:@"%@%@", unknownEntity, semicolon];
            NSLog(@"Unsupported XML character entity %@%@", unknownEntity, semicolon);
        }
    }
    while (![scanner isAtEnd]);

finish:
    return result;
}