About iOS Collection Views

Describes the use of collection views in iOS apps.

At a Glance

The standard iOS collection view classes provide all of the behavior you need to implement simple grids. You can also extend the standard classes to support custom layouts and specific interactions with those layouts.

A Collection View Manages the Visual Presentation of Data-Driven Views

A collection view facilitates the presentation of data-driven views provided by your app. The collection view’s only concern is taking your views and laying them out in a specific way. The collection view is all about the presentation and arrangement of your views and not about their content. Understanding the interactions between the collection view, its data source, the layout object, and your custom objects is crucial for using collection views in your app, particularly in smart and efficient ways.

Relevant chapters: Collection View Basics , Designing Your Data Source and Delegate

The Flow Layout Supports Grids and Other Line-Oriented Presentations

A flow layout object is a concrete layout object provided by UIKit. You typically use the flow layout object to implement grids—that is, rows and columns of items—but the flow layout supports any type of linear flow. Because it is not just for grids, you can use the flow layout to create interesting and flexible arrangements of your content both with and without subclassing. The flow layout supports items of different sizes, variable spacing of items, custom headers and footers, and custom margins without subclassing. And subclassing allows you to tweak the behavior of the flow layout class even further.

Relevant chapter: Using the Flow Layout

Gesture Recognizers Can Be Used for Cell and Layout Manipulations

Like all views, you can attach gesture recognizers to a collection view to manipulate the content of that view. Because a collection view involves the collaboration of multiple views, it helps to understand some basic techniques for incorporating gesture recognizers into your collection views. You can use gesture recognizers to tweak layout attributes or to manipulate items in a collection view.

Relevant chapter: Incorporating Gesture Support

Custom Layouts Let You Go Beyond Grids

You can subclass the basic layout object to implement custom layouts for your app. Even though designing a custom layout does not typically require a large amount of code, the more you understand how layouts work, the better you can design your layout objects to be efficient. The guide’s final chapter focuses on an example project with a full implementation of a custom layout.

Relevant chapters: Creating Custom Layouts , Custom Layouts: A Worked Example

Prerequisites

Before reading this document, you should have a solid understanding of the role views play in iOS apps. If you are new to iOS programming and not familiar with the iOS view architecture, read View Programming Guide for iOS before reading this book.

About iOS Collection Views

At a Glance

Prerequisites

See Also