Drag & drop (<NSDraggingDestination>) in Cocoa does not work

Question

I want to implement some "simple" drag & drop into my Mac application. I dragged in a view and entered "MyView" in my nib file accordingly.However I do not get any response in my console (I try to log messages whenever any of the protocol methods are triggered)

I have subclassed NSView like this:

@interface MyView : NSView <NSDraggingDestination>{
    NSImageView* imageView;
}

and implement it like this:

- (id)initWithFrame:(NSRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {

        [self registerForDraggedTypes:[NSImage imagePasteboardTypes]];

        NSRect rect = NSMakeRect(150, 0, 400, 300);
        imageView = [[NSImageView alloc] initWithFrame:rect];

        [imageView setImageScaling:NSScaleNone];
        [imageView setImage:[NSImage imageNamed:@"test.png"]];
        [self addSubview:imageView];



    }

    return self;
}


- (NSDragOperation)draggingEntered:(id <NSDraggingInfo>)sender{
    NSLog(@"entered");
    return NSDragOperationCopy;

}

- (NSDragOperation)draggingUpdated:(id <NSDraggingInfo>)sender{
    return NSDragOperationCopy;

}


- (void)draggingExited:(id <NSDraggingInfo>)sender{
    NSLog(@"exited");

}
- (BOOL)prepareForDragOperation:(id <NSDraggingInfo>)sender{
    NSLog(@"som");
    return YES;

}

- (BOOL)performDragOperation:(id<NSDraggingInfo>)sender {

    NSPasteboard *pboard = [sender draggingPasteboard];

    if ( [[pboard types] containsObject:NSURLPboardType] ) {
        NSURL *fileURL = [NSURL URLFromPasteboard:pboard];
        NSLog(@"%@", fileURL);
    }
    return YES;
}

- (void)concludeDragOperation:(id <NSDraggingInfo>)sender{
    NSLog(@"conclude sth");


}

- (void)draggingEnded:(id <NSDraggingInfo>)sender{
    NSLog(@"ended");


}

- (BOOL)wantsPeriodicDraggingUpdates{
    NSLog(@"wants updates");

}


- (void)updateDraggingItemsForDrag:(id <NSDraggingInfo>)sender NS_AVAILABLE_MAC(10_7){
}

Answer 1

If anyone still needs this, using:

[self registerForDraggedTypes:[NSArray arrayWithObjects: 
                       NSFilenamesPboardType, nil]];

instead of:

[self registerForDraggedTypes: 
                      [NSImage imagePasteboardTypes]]; // BAD: dropped image runs away, no draggingdestination protocol methods sent...

solved this problem for me. I suspect this works because my XIB is targeting osX 10.5. NSFilenamesPboardType represents a 10.5-and-previous 'standard data' UTI and [NSImage imagePasteboardTypes] returns 10.6-and-after standard data UTIs.

By the way, in - (BOOL)performDragOperation:(id NSDraggingInfo)sender, you can get a path for the file that was dropped with:

 NSArray *files = [pboard propertyListForType:NSFilenamesPboardType];

Got the solution here:

http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/DragandDrop/Tasks/acceptingdrags.html#//apple_ref/doc/uid/20000993-BABHHIHC