HTML entity encoding (convert '<' to '<') on iPhone in objective-c

Question

I\'m developing an application for the iPhone that has inApp-mail sending capabilities. So far so good, but now I want to avoid html-injections as some parts of the mail are

Answer 1

I'm expanding @Markus answer, because my case is i'm sending JSON string, so i need to added some escape, these are my function :

note : the exception reference from w3schools. https://www.w3schools.com/tags/ref_urlencode.asp

- (NSString*)convertStringToHTMLEscape:(NSString*)stringContent
{
    stringContent = [stringContent stringByReplacingOccurrencesOfString:@"{" withString:@"%7B"];
    stringContent = [stringContent stringByReplacingOccurrencesOfString:@"}" withString:@"%7D"];
    stringContent = [stringContent stringByReplacingOccurrencesOfString:@"[" withString:@"%5B"];
    stringContent = [stringContent stringByReplacingOccurrencesOfString:@"]" withString:@"%5D"];
    stringContent = [stringContent stringByReplacingOccurrencesOfString:@" " withString:@"%20"];
    stringContent = [stringContent stringByReplacingOccurrencesOfString:@"\"" withString:@"%22"];
    stringContent = [stringContent stringByReplacingOccurrencesOfString:@"\\" withString:@"%5C"];
    stringContent = [stringContent stringByReplacingOccurrencesOfString:@"/" withString:@"%2F"];

    return stringContent;
}