Re: Get list of possible applications

FROM : Gerd Knops
DATE : Sun Apr 20 17:15:28 2008

On Apr 19, 2008, at 11:33 PM, Chris Hanson wrote:
> On Apr 19, 2008, at 9:55 AM, Gerd Knops wrote:

>> This returns an array with URLs of applicable applications for a 
>> file of a given URL:
>>
>> - (NSArray *)applicationsForURL:(NSURL *)url {
>>     
>>     return (NSArray 
>> *)LSCopyApplicationURLsForURL((CFURLRef)url,kLSRolesAll);
>> }

>
> It also leaks -- even if you're running under Objective-C garbage 
> collection -- because LSCopyApplicationURLsForURL has "copy" in its 
> name and therefore follows the Core Foundation "copy" rule.
>

Sorry, careless copying from a larger context and failure to proof 
read... Of course Chris is right.

Gerd


> The proper form for the above method, if you aren't using Objective-
> C garbage collection, is:
>
>  - (NSArray *)applicationsForURL:(NSURL *)url {
>      return [(NSArray *)LSCopyApplicationURLsForURL((CFURLRef)url, 
> kLSRolesAll) autorelease];
>  }
>
> This ensures that the returned NSArray will be autoreleased, instead 
> of leaked.
>
> If you're using -- or might use -- Objective-C garbage collection, 
> you'll want to replace the cast to (NSArray *) with NSMakeColectable 
> like this:
>
>  - (NSArray *)applicationsForURL:(NSURL *)url {
>      return 
> [NSMakeCollectable(LSCopyApplicationURLsForURL((CFURLRef)url, 
> kLSRolesAll)) autorelease];
>  }
>
> The NSMakeCollectable ensures that the CFArrayRef returned by 
> LSCopyApplicationURLsForURL will have its lifetime managed by the 
> collector if GC is on, since -autorelease has no effect when GC is 
> on.  This is also correct for non-GC, since NSMakeCollectable when 
> GC is off is effectively just a cast from (CFTypeRef) to (id).
>
>  -- Chris
>