Encode NSString for XML/HTML

Question

Is there a way to HTML encode a string (NSString) in Objective-C, something along the lines of Server.HtmlEncode in .NET?

Answer 1

I use Google Toolbox for Mac (works on iPhone). In particular, see the additions to NSString in GTMNSString+HTML.h and GTMNSString+XML.h.

Answer 2

Refer below answer:

NSString *content = global.strPrivacyPolicy;
content =  [[[[[content stringByReplacingOccurrencesOfString: @"&" withString: @"&"]
stringByReplacingOccurrencesOfString:@"""  withString:@"\" "]
stringByReplacingOccurrencesOfString: @"'"  withString:@"'"]
stringByReplacingOccurrencesOfString: @">" withString: @">"]
stringByReplacingOccurrencesOfString:  @"&lt;" withString:@"<"];
[_webViewPrivacy loadHTMLString:content baseURL:nil];

Answer 3

For URL encoding:

NSString * encodedString = [originalString
      stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding];

See Apple's NSString documentation for more info.

For HTML encoding:

Check out CFXMLCreateStringByEscapingEntities, which is part of the Core Foundation XML library, but should still do the trick.

Answer 4

This easiest solution is to create a category as below:

Here’s the category’s header file:

#import <Foundation/Foundation.h>
@interface NSString (URLEncoding)
-(NSString *)urlEncodeUsingEncoding:(NSStringEncoding)encoding;
@end

And here’s the implementation:

#import "NSString+URLEncoding.h"
@implementation NSString (URLEncoding)
-(NSString *)urlEncodeUsingEncoding:(NSStringEncoding)encoding {
    return (NSString *)CFURLCreateStringByAddingPercentEscapes(NULL,
               (CFStringRef)self,
               NULL,
               (CFStringRef)@"!*'\"();:@&=+$,/?%#[]% ",
               CFStringConvertNSStringEncodingToEncoding(encoding));
}
@end

And now we can simply do this:

NSString *raw = @"hell & brimstone + earthly/delight";
NSString *url = [NSString stringWithFormat:@"http://example.com/example?param=%@",
            [raw urlEncodeUsingEncoding:NSUTF8StringEncoding]];
NSLog(url);

The credits for this answer goes to the website below:-

http://madebymany.com/blog/url-encoding-an-nsstring-on-ios

Answer 5

I found the only way that uses only built-in functions (not manual parsing) and covers all cases. Requires AppKit/UIKit in addition to Foundation. This is Swift but can easily be Objective-C:

func encodedForHTML() -> String {

    // make a plain attributed string and then use its HTML write functionality
    let attrStr = NSAttributedString(string: self)

    // by default, the document outputs a whole HTML element
    // warning: if default apple implementation changes, this may need to be tweaked
    let options: [NSAttributedString.DocumentAttributeKey: Any] = [
            .documentType: NSAttributedString.DocumentType.html,
            .excludedElements: [
                "html",
                "head",
                "meta",
                "title",
                "style",
                "p",
                "body",
                "font",
                "span"
            ]
    ]

    // generate data and turn into string
    let data = try! attrStr.data(from: NSRange(location: 0, length: attrStr.length), documentAttributes: options)
    let str = String(data: data, encoding: .utf8)!

    // remove <?xml line
    return str.components(separatedBy: .newlines).dropFirst().first!
}

Answer 6

If you can use NSXMLNode (on OS X) Here is the trick:

NSString *string = @"test<me>"
NSXMLNode *textNode = [NSXMLNode textWithStringValue:string];
NSString *escapedString = [textNode.XMLString];