Comparing NSCollectionView and UICollectionView #3

Photo by Ilya Pavlov

The biggest difference for NSCollectionView in macOS is the support of Drag & Drop. It is served through a set of NSCollectionViewDelegate methods.

Drag & Drop Support

In macOS, keyboard and mouse (including TrackPad and Magic Mouse) are the most common forms of input. Drag & Drop is based on the mouse control. User can do the followings:

1. Drag a rectangle to highlight the items within the area
2. Drag the selected items to a different position within the collection view
3. Drag the selected items to anywhere else that allows drop, both within and outside the application

Typically, Drag & Drop will go through a life cycle as below:

1. Create a Pasteboard to hold the dragging data
2. Check whether the drag can start
3. Start a dragging session
4. Validate the Drop in an area
5. Accept the Drop
6. End a dragging session

Each of these lifecycle methods has a corresponding delegate method.

Here is a video demonstrating a simple use of Drag & Drop in NSCollectionView.

Layout Handling in UICollectionView

In comparison, iOS provides more delegate APIs to handle layout changes. There are 4main categories

• Tracking the Addition and Removal of Views
• Handling Layout Changes
• Managing Actions for Cells
• Managing Focus in a Collection View

If you want to implement something like Drag & Drop, a long press together with a pan gesture would be a nice place to get started.

I am taking a challenge to write a post every day for 180 days. The content will be related to my life as a father, entrepreneur, developer and trainer.

Recent Articles:

Comparing NSCollectionView and UICollectionView #1

Comparing NSCollectionView and UICollectionView #2