Re: no subject

[Sebastian Reitenbach]

Richard Frith-Macdonald <richard@tiptree.demon.co.uk> wrote: 
> 
> On 14 Apr 2008, at 11:56, Richard Frith-Macdonald wrote:
> 
> >
> > On 14 Apr 2008, at 10:41, Sebastian Reitenbach wrote:
> >
> >> Hi,
> >>
> >> I tried to download a csv file from a webserver.I found an example  
> >> using
> >> NSURL.
> >> As the documentation says, NSURL needs an
> >> escaped string, so I used
> >> stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding, so  
> >> I wrote
> >> the test below:
> >> =================Sample Program================================
> >> #include <Foundation/Foundation.h>
> >>
> >> int
> >> main(int argc, const char *argv[])
> >> {
> >> id pool = [[NSAutoreleasePool alloc] init];
> >>
> >> NSString *GKey =
> >> 
@"ABQIAAAAvp3__HwvT3VkixIIbsW0axQuKI_6t1bH2P0vCI_Q8jfpn8qdNBQMnneljxh9czilkau_bYSCXteS_A

> >> ";
> >>
> >>
> >>
> >> NSString *Address = @"Potsdamer+Platz+Berlin+Germany";
> >> NSString *URLString = [NSString
> >> stringWithFormat:@"http://maps.google.com/maps/geo?q= 
> >> %@&output=csv&key=%@",
> >> Address, GKey];
> >> URLString = [URLString
> >> stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
> >
> > That last line is wrong ... the method is for fixing strings which  
> > are not legal as parts of a URL so that they can be used within a  
> > URL ... if you apply the method to en entire URL, what you get is  
> > obviously not a URL, but rather a string containing characters which  
> > are legal to put inside a URL.
> > While the first sentence of the GNUstep documentation for the method  
> > is perhaps unclear (I've tried to clarify it), the remainder of the  
> > documentation goes on to explain exactly what the method does.  It  
> > also warns that, where you are filling in form fields (as in the  
> > example above), you need to perform additional escaping for '+','='  
> > and '&' because the implementation does not do that for you (to  
> > maintain macos compatibility).
> 
thanks for clarifying, then I obviously misunderstood it a bit. 


> 
> Something like the following function might be what you want for  
> handling form data:
> 
> NSString*
> URLFormField(NSString *value)
> {
>    static NSCharacterSet *illegtal = nil;
>    NSRange r;
> 
>    if (illegal == nil)
>      {
>        illegal = [[NSCharacterSet characterSetWithCharactersInString:  
> @"+=&"] retain];
>      }
>    value = [value stringByAddingPercentEscapesUsingEncoding:  
> NSUTF8StringEncoding];
>    r = [value rangeOfCharacterFromSet: illegal];
>    if (r.length > 0)
>      {
>        NSMutableString *m = [value mutableCopy];
> 
>        while (r.length > 0)
>          {
>            switch ([m characterAtIndex: r.location])
>              {
>             case '+': [m replaceCharactersInRange: r withString: @"%2B"];  
> break;
>             case '=': [m replaceCharactersInRange: r withString: @"%3D"];  
> break;
>             default: [m replaceCharactersInRange: r withString: @"%26"];  
> break;
>              }
>            r = [m rangeOfCharacterFromSet: illegal];
>         }
>        value = [m autorelease];
>      }
>    return value;
> }
> 
ah, thanks a lot for this example, seems very helpful.

kind regards
Sebastian