过滤html标签（修改版）

- (NSString *)flattenHTML:(NSString *)html {
    
    NSScanner *theScanner;
    NSString *text = nil;
    
    theScanner = [NSScanner scannerWithString:html];
    
    while ([theScanner isAtEnd] == NO) {
        
        // find start of tag
        [theScanner scanUpToString:@"<" intoString:NULL] ; 
        
        // find end of tag
        [theScanner scanUpToString:@">" intoString:&text] ;
        
        // replace the found tag with a space
        //(you can filter multi-spaces out later if you wish)
        NSRange range = [text rangeOfString:@"<" options:NSBackwardsSearch];
        if (range.location != 0) {
            text = [text substringFromIndex:range.location];
        }
        html = [html stringByReplacingOccurrencesOfString:
                [ NSString stringWithFormat:@"%@>", text]
                                               withString:@" "];
        
    } // while //
    
    return html;
    
}