JLNDragEffectManager is a small, simple Objective-C class for Cocoa that gives you the morphing animation as seen when dragging controls from the palette in Interface Builder 3.


I wrote a post titled “Your Very Own Drag Show with JLNDragEffectManager” with a full explanation of the design decisions, goals, and a basic video demonstration.

I later wrote a post titled “Drag Effect In Action” to demonstrate how this code is used in a real-world application, XTabulator.


  • Download the source and demo project below.
  • Add JLNDragEffectManager to your project.
  • Add the QuartzCore to your project’s linked frameworks.
  • Remember to include JLNDragEffectManager.h.
  • Override the three view dragging methods.

The code below shows how to use this effect manager in your custom view. The three main drag-and-drop methods are overridden to call the manager’s corresponding methods.


- (void)draggedImage:(NSImage *)anImage beganAt:(NSPoint)aPoint
// Let's figure out our geometry. For shits-n-giggles, we'll
// make the whole window our source screen rect, and the
// current mouse position (at start of drag) as the slide-back point
NSPoint startPointInScreen = [NSEvent mouseLocation];
NSRect sourceScreenRect = [[self window] frame];

// Let’s use some images reminiscent of Interface Builder’s
// drag-from-Library-palette-to-make-a-real-object effect
NSImage * insideImage = [NSImage imageNamed:@"textfieldasicon"];
NSImage * outsideImage = [NSImage imageNamed:@"textfieldrealized"];

// Don the boas and start the drag show!
[[JLNDragEffectManager sharedDragEffectManager]

- (void)draggedImage:(NSImage *)draggedImage movedTo:(NSPoint)screenPoint
// Update the position
[[JLNDragEffectManager sharedDragEffectManager] updatePosition];

- (void)draggedImage:(NSImage *)anImage endedAt:(NSPoint)aPoint
// End the drag show, clean up the glitter and sweat-and-masquera
// puddles and call it a day
[[JLNDragEffectManager sharedDragEffectManager]

// Do any other processing you might need, including going home to
// your cats and wig collection
// …



This source code is free to use in any private, public, or commercial software products, with attribution. See the full license included with the source code.

Source & Demo

This project is now hosted on Github.

Projects in Which JLNDragEffectManager is Used

Use the drag effect manager in your app? Let me know and I’ll post a link.

© Joshua Nozzi. All rights reserved.