If you are n00b when it comes to iPhone development, then you’ve come to the right place! We’ll be posting howtos, tips and tricks continuously.
So, how do you URL enconde a string? It’s quite simple if you know how. 
+ (NSString *)urlEncodeValue:(NSString *)str { NSString *result = (NSString *) CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (CFStringRef)str, NULL, CFSTR(”:/?#[]@!$&’()*+,;=”), kCFStringEncodingUTF8); return [result autorelease]; }
To create an URL object, do like this:
[NSURL URLWithString:encodedUrlString]
#1 by Peter Strömberg on April 8, 2009 - 23:06
Ah, an iPhone category. Nice! Could someone explain to me why encoding is such a tricky subject? =)
#2 by onitake on April 27, 2009 - 17:55
unfortunately, this will not correctly escape characters reserved as uri part delimiters or sub-part delimiters.
if you want to do that roll your own converter or use CFURLCreateStringByAddingPercentEscapes instead. as you might already know, corefoundation is toll-free bridged to foundation, so you can just cast between cfstring and nsstring. but don’t forget to release/autorelease.
example:
NSString *encodedString = (NSString *) CFURLCreateStringByAddingPercentEscapes(NULL, (CFStringRef) unencodedString, NULL, NULL, kCFStringEncodingUTF8);
if you want to make it rfc 3986-safe, use the following code:
CFStringRef escapeChars = (CFStringRef) @”:/?#[]@!$&’()*+,;=”;NSString *encodedString = (NSString *) CFURLCreateStringByAddingPercentEscapes(NULL, (CFStringRef) unencodedString, NULL, escapeChars, kCFStringEncodingUTF8);
#3 by Samuel on April 27, 2009 - 21:09
Thanks, that’s correct! I have edited the post!
+ (NSString *)urlEncodeValue:(NSString *)str
{
NSString *result = (NSString *) CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (CFStringRef)str, NULL, CFSTR(“:/?#[]@!$&’()*+,;=”), kCFStringEncodingUTF8);
return [result autorelease];
}
#4 by Dan J on August 26, 2009 - 19:02
I think you need to include ” in the list of escaped characters. Don’t forget to escape it in code, e.g.
CFSTR(”:/?#[]@!$&’()*+,;=\””)
http://en.wikipedia.org/wiki/Percent-encoding
This was very useful – thanks!
#5 by sugiarto on November 23, 2009 - 23:56
Thanks,
very help me..
#6 by me on June 16, 2010 - 09:38
be sure to replace the ” with regular quotes when copy & paste this function … otherwise the compiler will get an error …