DragAndDropWithNSViewSubclass

Here’s a simple drag and drop example for filenames dragged from the finder –zootbobbalu

Header

#import <AppKit/AppKit.h>

@interface TestDragAndDropView : NSView { NSColor *backgroundColor, *blueColor, *greenColor; }

@end

Source

#import “TestDragAndDropView.h”

@implementation TestDragAndDropView

(id)initWithFrame:(NSRect)frame { self = [super initWithFrame:frame]; if (self) { NSArray *draggedTypeArray = [NSArray arrayWithObjects:NSFilenamesPboardType, nil]; [self registerForDraggedTypes:draggedTypeArray];

  /*
    
      Since I'm not aware of any documentation explicitly telling
      you not to retain preset colors, I'm going to retain them 
      anyways!!
    
  */
    
    
  blueColor = backgroundColor = [[NSColor blueColor] retain];
  greenColor = [[NSColor greenColor] retain];    }   return self; }

(void)dealloc { [blueColor release]; blueColor = nil; [greenColor release]; greenColor = nil;

[super dealloc]; }
(void)drawRect:(NSRect)rect { [backgroundColor set]; NSRectFill([self visibleRect]); }

(NSDragOperation)draggingEntered:(id )sender { NSPasteboard *pboard = [sender draggingPasteboard]; NSArray *filenames = [pboard propertyListForType:NSFilenamesPboardType]; NSLog(@"draggingEntered: filenames: %@", [filenames description]); NSArray *supportedFiletypes = [NSArray arrayWithObjects:@"txt", @"rtf", @"html", @"htm", @"pdf", nil]; int dragOperation = NSDragOperationNone; if ([filenames count]) {

  /*
      Decide here if you accept the filenames that are dragged into the view.
      If you do accept the dragged filenames then set dragOperation to 
      NSDragOperationCopy:
        
          dragOperation = NSDragOperationCopy;
            
      Here is where you can give some user feedback if the filenames
      are valid files (e.g. change a boarder color or the background color of the view)
            
  */
    
  NSEnumerator *filenameEnum = [filenames objectEnumerator]; 
  NSString *filename;
  dragOperation = NSDragOperationCopy;
  while (filename = [filenameEnum nextObject]) {
      if (![supportedFiletypes containsObject:[filename pathExtension]]) {
          dragOperation = NSDragOperationNone;
          break;
      }
  }
  if (dragOperation == NSDragOperationCopy) backgroundColor = greenColor;   }          [self setNeedsDisplay:YES];   return dragOperation; }

-(void)draggingExited:(id )sender { NSPasteboard *pboard = [sender draggingPasteboard]; NSArray *filenames = [pboard propertyListForType:NSFilenamesPboardType]; backgroundColor = blueColor; [self setNeedsDisplay:YES]; NSLog(@"draggingExited: filenames: %@", [filenames description]); }

(BOOL)performDragOperation:(id )sender { NSPasteboard *pboard = [sender draggingPasteboard]; NSArray *filenames = [pboard propertyListForType:NSFilenamesPboardType]; BOOL didPerformDragOperation = NO; NSLog(@"performDragOperation: filenames: %@", [filenames description]); if ([filenames count]) {
```
  /*
        
      Do something here with filenames and 
      decide if a dragging operation was actually performed.
      If an operation was performed set didPerformDragOperation
      to YES:
        
          didPerformDragOperation = YES;
    
  */
```
} backgroundColor = blueColor; [self setNeedsDisplay:YES]; return didPerformDragOperation; }

-(void)concludeDragOperation:(id )sender {

/*
    This method gives you the chance to change any state variables that
    deal with dragAndDrop.

*/

NSLog(@"concludeDragOperation:"); }

@end

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