Wondering if there is an easy way to do a simple HTML escape/unescape in Objective C. What I want is something like this psuedo code:
NSString *string = @"<span>Foo</span>";
[string stringByUnescapingHTML];
Which returns
<span>Foo</span>
Hopefully unescaping all other HTML entities as well and even ASCII codes like Ӓ and the like.
Is there any methods in Cocoa Touch/UIKit to do this?
This link contains the solution below. Cocoa CF has the CFXMLCreateStringByUnescapingEntities function but that's not available on the iPhone.
@interface MREntitiesConverter : NSObject {
NSMutableString* resultString;
}
@property (nonatomic, retain) NSMutableString* resultString;
- (NSString*)convertEntiesInString:(NSString*)s;
@end
@implementation MREntitiesConverter
@synthesize resultString;
- (id)init
{
if([super init]) {
resultString = [[NSMutableString alloc] init];
}
return self;
}
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)s {
[self.resultString appendString:s];
}
- (NSString*)convertEntiesInString:(NSString*)s {
if(s == nil) {
NSLog(@"ERROR : Parameter string is nil");
}
NSString* xmlStr = [NSString stringWithFormat:@"<d>%@</d>", s];
NSData *data = [xmlStr dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];
NSXMLParser* xmlParse = [[[NSXMLParser alloc] initWithData:data] autorelease];
[xmlParse setDelegate:self];
[xmlParse parse];
return [NSString stringWithFormat:@"%@",resultString];
}
- (void)dealloc {
[resultString release];
[super dealloc];
}
@end
What about the NSString methods:
- (NSString *)stringByAddingPercentEscapesUsingEncoding:(NSStringEncoding)encoding
- (NSString *)stringByReplacingPercentEscapesUsingEncoding:(NSStringEncoding)encoding
Those do exist on the iPhone. I know you were asking for more the HTML variant though, which this is not...
MREntitiesConverter doesn't work for escaping malformed xml. It will fail on a simple URL:
http://www.google.com/search?client=safari&rls=en&q=fail&ie=UTF-8&oe=UTF-8
The MREntitiesConverter above is an HTML stripper, not encoder.
If you need an encoder, go here: http://stackoverflow.com/questions/803676/encode-nsstring-for-xml-html
When I try the MREntitiesConverter, the XML parser gives an error to the delegate parser:parseErrorOccurred:
Error Domain=NSXMLParserErrorDomain Code=64 "Operation could not be completed. (NSXMLParserErrorDomain error 64.)
Looking in NSXML.h I find
error 64 = NSXMLParserMisplacedXMLDeclarationError
Does wrapping the XML data in another tag potentially produce incorrect XML? For example, if the XML data has an XML declaration/header at the beginning e.g. "". Putting this header inside a tag seems like incorrect XML.
I guess I need to strip this header? Any other ideas?
I should add I was trying to unHTML encode an entire XML document that had HTML encoding inside. Why? Well, this is what I get back from Yahoo's Soap API.
Check out my NSString category for HTML. Here are the methods available:
- (NSString *)stringByConvertingHTMLToPlainText;
- (NSString *)stringByDecodingHTMLEntities;
- (NSString *)stringByEncodingHTMLEntities;
- (NSString *)stringWithNewLinesAsBRs;
- (NSString *)stringByRemovingNewLinesAndWhitespace;
This is an easy to use NSString category implementation:
It is far from complete but you can add some missing entities from here: http://code.google.com/p/statz/source/browse/trunk/NSString%2BHTML.m
Usage:
#import "NSString+HTML.h"
NSString *raw = [NSString stringWithFormat:@"<div></div>"];
NSString *escaped = [raw htmlEscapedString];
The links Blago posted are helpful, I was able to add ( @"'", @"'" ) But line 51 of the NSSting+HTML.m file needs to return htmlUnescapes; (not htmlEscapes)
This is an incredibly hacked together solution I did, but if you want to simply escape a string without worrying about parsing, do this:
-(NSString *)htmlEntityDecode:(NSString *)string
{
string = [string stringByReplacingOccurrencesOfString:@""" withString:@"\""];
string = [string stringByReplacingOccurrencesOfString:@"'" withString:@"'"];
string = [string stringByReplacingOccurrencesOfString:@"&" withString:@"&"];
string = [string stringByReplacingOccurrencesOfString:@"<" withString:@"<"];
string = [string stringByReplacingOccurrencesOfString:@">" withString:@">"];
return string;
}
I know it's by no means elegant, but it gets the job done. You can then decode an element by calling:
string = [self htmlEntityDecode:string];
Like I said, it's hacky but it works. IF you want to encode a string, just reverse the stringByReplacingOccurencesOfString parameters.