Because it is not a method a classic NSString respond to, you can though add a category like the following, to add the method yourself :
@interface NSString (URLDecode)
- (NSString *)URLDecode;
@end
@implementation NSString
- (NSString *)URLDecode
{
NSString *result = [(NSString *)self stringByReplacingOccurrencesOfString:@"+" withString:@" "];
result = [result stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
return result;
}
@end