Drag and Drop with NSStatusItem

问题:

I'm trying to write an application that allows the user to drag files from the Finder and drop them onto an NSStatusItem. So far, I've created a custom view that implements the drag and drop interface. When I add this view as a subview of an NSWindow it all works correctly -- the mouse cursor gives appropriate feedback, and when dropped my code gets executed.

However, when I use the same view as an NSStatusItem's view it doesn't behave correctly. The mouse cursor gives appropriate feedback indicating that the file can be dropped, but when I drop the file my drop code never gets executed.

Is there something special I need to do to enable drag and drop with an NSStatusItem?

回答1:

I finally got around to testing this and it works perfectly, so there's definitely something wrong with your code.

Here's a custom view that allows dragging:

@implementation DragStatusView

- (id)initWithFrame:(NSRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        //register for drags
        [self registerForDraggedTypes:[NSArray arrayWithObjects: NSFilenamesPboardType, nil]];
    }

    return self;
}

- (void)drawRect:(NSRect)dirtyRect
{
    //the status item will just be a yellow rectangle
    [[NSColor yellowColor] set];
    NSRectFill([self bounds]);
}

//we want to copy the files
- (NSDragOperation)draggingEntered:(id<NSDraggingInfo>)sender
{
    return NSDragOperationCopy;
}

//perform the drag and log the files that are dropped
- (BOOL)performDragOperation:(id <NSDraggingInfo>)sender 
{
    NSPasteboard *pboard;
    NSDragOperation sourceDragMask;

    sourceDragMask = [sender draggingSourceOperationMask];
    pboard = [sender draggingPasteboard];

    if ( [[pboard types] containsObject:NSFilenamesPboardType] ) {
        NSArray *files = [pboard propertyListForType:NSFilenamesPboardType];

        NSLog(@"Files: %@",files);
    }
    return YES;
}


@end

Here's how you'd create the status item:

NSStatusItem* item = [[[NSStatusBar systemStatusBar] statusItemWithLength:NSSquareStatusItemLength] retain];

DragStatusView* dragView = [[DragStatusView alloc] initWithFrame:NSMakeRect(0, 0, 24, 24)];
[item setView:dragView];
[dragView release];

回答2:

Since Yosemite, the method for setting a view on NSStatusItem is deprecated but fortunately there is a much nicer way using the new NSStatusItemButton property on NSStatusItem:

- (void)applicationDidFinishLaunching: (NSNotification *)notification {
    NSImage *icon = [NSImage imageNamed:@"iconName"];
    //This is the only way to be compatible to all ~30 menu styles (e.g. dark mode) available in Yosemite
    [normalImage setTemplate:YES];
    statusItem.button.image = normalImage;

    // register with an array of types you'd like to accept
    [statusItem.button.window registerForDraggedTypes:@[NSFilenamesPboardType]];
    statusItem.button.window.delegate = self;

}

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

- (BOOL)performDragOperation:(id<NSDraggingInfo>)sender {
  //drag handling logic
}

Please be aware that the button property is only available starting in 10.10 and you might have to keep your old solution if you support 10.9 Mavericks or below.