dragging from a view to editors and the finder

FROM : Nestor Cardozo
DATE : Mon Apr 18 13:00:22 2005

This has been discussed previously in the list, but I cannot find a
coherent solution.

I have implemented a view in my application to be a drag source.

My code looks like this:

-(unsigned int)draggingSourceOperationMaskForLocal:(BOOL)isLocal
{
   return NSDragOperationCopy;
}

- (void)mouseDragged:(NSEvent *)event
{
   NSPasteboard *pb = [NSPasteboard pasteboardWithName:NSDragPboard];
   [pb declareTypes:
       [NSArray arrayWithObject:NSPDFPboardType]
             owner:self];
   NSRect r = [self bounds];
   NSData *data = [self dataWithPDFInsideRect:r];
   [pb setData:data forType:NSPDFPboardType];
   NSImage *anImage = [[[NSImage alloc] initWithSize:[self bounds].size]
autorelease];
   [anImage lockFocus];
   [self drawRect:[self bounds]];
   [anImage unlockFocus];
   NSPoint p = [self convertPoint:[event locationInWindow] fromView:nil];
    NSSize s = [anImage size];
   p.x = p.x - s.width/2;
   p.y = p.y - s.height/2;
   [self dragImage:anImage
                at:p
            offset:NSMakeSize(0,0)
             event:event
        pasteboard:pb
            source:self
         slideBack:YES];
}

Currently I can drag the contents of the view and drop it to
applications such as textedit, easycrop, illustrator (but strangely not
keynote). My problem is that I cannot drag from my view to the finder.
I understand I should implement

- (BOOL)dragPromisedFilesOfTypes:(NSArray *)typeArray
fromRect:(NSRect)aRect source:(id)sourceObject
slideBack:(BOOL)slideBack event:(NSEvent *)theEvent


and

- (NSArray *)namesOfPromisedFilesDroppedAtDestination:(NSURL
*)dropDestination

But, if I understand well these methods assume that you already have a
file. Should I create a file within my mouseDragged method? Does anyone
have an example (code) where this has been done. I have checked apple
documentation but all I can find is a couple of paragraphs on dragging
file promises.

thanks for your help