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Asset Catalog Format Reference

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Types Overview

The folders in asset catalogs represent the overall asset catalog, groups of assets and other groups, and several different types of assets. Some of the asset types in a catalog work only with selected Apple platforms.

Content Types

The type of content represented by a folder is encoded in the extension for the name of the folder. For example, a folder named PosingLlamas.imageset has a type of imageset.

Table 5-1 lists the content types, folder name extension, and a brief description of each type.

Table 5-1Content types

Folder type

Extension

Description

App Icon Type

.appiconset

The various sizes of the icon for an iOS or watchOS app.

 

Children are .png files.

AR Reference Image

.arimageset

An image file for an ARReferenceImage. Supported file formats include HEIF (High Efficiency Image Format), JPEG, PNG, and TIFF.

AR Resource Group

.arresourcegroup

A group of reference images for ARKit.

 

Children are AR Reference Image folders.

Brand Assets Type

.brandassets

The layered app icons and top shelf image for your app.

 

Children are image stacks and image sets.

Catalog Type

.xcassets

The top level folder for the asset catalog.

 

Children are any valid asset type except Catalog.

Cube Texture Type

.cubetextureset

A 3D texture mapped onto a cube.

 

Children are .mipmapset folders.

Data Set Type

.dataset

Used to include arbitrary app data.

 

Children are files in any format except binary executable code.

GameCenter Dashboard Image Set Type

.gcdashboardimage

Images for the logos in a GameCenter dashboard.

 

Children are image sets.

GameCenter Leaderboard Type

.gcleaderboard

Background image stack for a GameCenter leaderboard.

 

Children are image stacks.

GameCenter Leaderboard Set Type

.gcleaderboardset

Background image stack for a GameCenter leaderboard set.

 

Children are image stacks.

Group Type

None.

No period (.) can appear in the name of the group.

A group of other elements.

 

Children are any valid asset type except Catalog.

Icon Set Type

.iconset

A replica of the .iconset format for OS X apps.

 

Children are .png files.

Image Set Type

.imageset

An image used for UIImage, NSImage, user interface controls, and other objects using images.

 

Children are HEIF(High Efficiency Image Format), .png, .jpg, .pdf files.

Image Stack Type

.imagestack

A set of layered images combined to enable parallax.

 

Children are image stack layers.

Image Stack Layer Type

.imagestacklayer

A layer in an image stack.

 

Children are image sets.

Launch Image Type

.launchimage

Support for app launch images.

 

Children are .png files.

Mipmap Type

.mipmapset

An optimized set of texture images at different resolutions.

 

Children are files for the different resolutions.

Named Color Type

.colorset

A named color. The name of the color can be used anywhere in an Xcode project.

Sprite Atlas Type

.spriteatlas

The image sets used for an SKTextureAtlas class.

 

Children are image set asset folders.

Sticker Type

.sticker

A sticker for a sticker pack.

 

Child is the image for the sticker.

Sticker Pack Type

.stickerpack

A pack of stickers for messaging.

 

Children are .stickersequence and .sticker folders.

Sticker Sequence Type

.stickersequence

A set of images for an animated sticker.

 

Children are the images for the animation.

Texture Type

.textureset

A 2D texture.

 

Children are .mipmapset folders.

Watch Complications Type

.complicationset

The image sets used for the different types of watch complications.

 

Children are image set folders.

Contents.json File

The Contents.json file specifies metadata for the asset catalog, attributes for a folder type, and attributes for asset files. Table 5-2 shows whether a Contents.json file is required, optional, or not used for each folder type.

Table 5-2Contents.json file required

Folder type

Contents.json

App Icon Type

Required

Brand Assets Type

Required

Catalog Type

Optional

Cube Texture Type

Required

Data Set Type

Required

GameCenter Dashboard Image Set Type

Optional

GameCenter Leaderboard Type

Optional

GameCenter Leaderboard Set Type

Optional

Group Type

Optional

Icon Set Type

None

Image Set Type

Required

Image Stack Type

Required

Image Stack Layer Type

Optional

Launch Image Type

Required

Mipmap Type

Required

Sprite Atlas Type

Optional

Sticker Type

Required

Sticker Pack Type

Required

Sticker Sequence Type

Required

Texture Type

Required

Watch Complications Type

Required

Platform Types

Table 5-3 shows the valid platforms for each folder type.

Table 5-3Folder type platforms

Element

iOS

OS X

tvOS

watchOS

App Icon Type

Brand Assets Type

Catalog Type

Cube Texture Type

Data Set Type

GameCenter Dashboard Image Set Type

GameCenter Leaderboard Type

GameCenter Leaderboard Set Type

Group Type

Icon Set Type

Image Set Type

Image Stack Type

Image Stack Layer Type

Launch Image Type

Mipmap Type

Sprite Atlas Type

Sticker Type

Sticker Pack Type

Sticker Sequence Type

Texture Type

Watch Complications Type