Asset Catalog Format Reference: Image Set Type

Image Set Type

The graphical image files for a named image asset used for instances of UIImage and NSImage.

Extension

.imageset

Folder Contents

.avci, .heic, .heif, .png, .jpg, and .pdf files.

Contents.json File (Required)

Metadata, on-demand resource tags, App Slicing properties, and attributes for the individual resource files (Table 18-1).

**Table 18-1**Image set tags
Key	Type	Description
`info`	Dictionary	Versioning information for the asset catalog.
`author`	String	The application that authored the asset catalog.
`version`	Number	The version of the asset catalog.
`properties`	Dictionary	Properties for the image set.
`on-demand-resource-tags`	Array of strings	The on-demand resource tags for the image set.
`preserves-vector-representation`	Boolean	Set to `true` to preserve the vector information for a PDF file.
`images`	Array of dictionaries	The images in the image set.
`color-space`	Slot component	The color space for the item. For the values, see color-space below.
`compression-type`	Slot component	The compression used on the item. For the values, see compression-type below.
`display-gamut`	Slot component	The color gamut of the device display. For the values, see display-gamut below.
`filename`	String	The `HEIF`, `.png`, `.jpg`, or `.pdf` file for the image.
`graphics-feature-set`	Slot component	The graphics features required for the image. For the values, see graphics-feature-set below.
`idiom`	Slot component	The device type for the image. For the values, see idiom below.
`language-direction`	String	The horizontal display direction for the image. For the values, see language-direction below.
`memory`	Slot component	The memory required by the data item. For the values, see memory below.
`scale`	Slot component	The scale of the image. For the values, see scale below.
`screen-width`	Slot component	The Apple Watch screen width for the image. For the values, see screen-width below.
`template-rendering-intent`	String	Specifies if the image is a template for use with visual effects such as replacing colors. For the values, see template-rendering-intent below.
`width-class`	Slot component	The size class for the width of the image. For the values, see width-class below.
`height-class`	Slot component	The size class for the height of the image. For the values, see height-class below.
`unassigned`	Boolean	Used by Xcode.
`alignment-insets`	Dictionary	The insets for `alignmentRectInsets` in `UIImage` or for `alignmentRect` in `NSImage`. The inset tag can be omitted.
`top`	Number	The top inset in pixels.
`bottom`	Number	The bottom inset in pixels.
`left`	Number	The left inset in pixels.
`right`	Number	The right inset in pixels.
`resizing`	Dictionary	The attributes for a resizable image. Only included with resizable images.
`mode`	Enum	The resizing mode of the image. For the values, see resizing mode below.
`center`	Dictionary	Used for resizing the image.
`mode`	Enum	The center resizing mode for the image. For the values, see center mode below.
`width`	Number	The width in pixels of the rectangle for the resizable area of the image. Only valid for modes of `3-part-horizontal` and `9-part`.
`height`	Number	The height in pixels of the rectangle for the resizable area of the image. Only valid for modes of `3-part-vertical` and `9-part`.
`cap-insets`	Dictionary	The inset from the edges of the image to the resizable area.
`top`	Number	The height in pixels of the non-resizable slice on the top of the image.
`bottom`	Number	The height in pixels of the non-resizable slice on the bottom of the image.
`left`	Number	The width in pixels of the non-resizable slice on the left of the image.
`right`	Number	The width in pixels of the non-resizable slice on the right of the image.

Values for Enumerated Tags

color-space

The color space for the image (Table 18-2).

**Table 18-2**`color-space` values
Value	Description
Tag not included	The image uses the standard sRGB color space.
`srgb`	The image uses the standard sRGB color space.
`display-p3`	The image uses a wide gamut color space.

compression-type

The type of compression used for the item (Table 18-3).

**Table 18-3**`compression-type` values
Value	Description
Tag not included	The compression type inherits from the parent. The type is set to lossless compression if there is no parent.
`automatic`	The image uses an automatic lossy compression.
`gpu-optimized-best`	The image uses a lossy GPU compression format optimized for quality.
`gpu-optimized-smallest`	The image uses a lossy GPU compression format optimized for memory size.
`lossless`	The image uses lossless compression. This is the default if the `compresson-type` tag is not included.
`lossy`	The image uses basic lossy compression.

display-gamut

The color gamut for the device display (Table 18-4).

**Table 18-4**`display-gamut` values
Value	Description
Tag not included	The image uses the standard sRGB color space.
`sRGB`	The image uses the standard sRGB color space.
`display-P3`	The image uses a wide gamut color space.

graphics-feature-set

The graphics feature set required for the item. The values correspond to values in the MTLFeatureSet enumerated type. The keys are based on the iOS types. tvOS uses the GPU and OS revision level equivalent keys. For example, metal2v3 corresponds to MTLFeatureSet_iOS_GPUFamily2_v3 on iOS and to MTLFeatureSet_tvOS_GPUFamily1_v2 on tvOS.

For values, see (Table 18-5).

**Table 18-5**`graphics-feature-set` values
Value	Description
Tag not included	The item works with any device that has at least OpenGL ES 2.0.
`metal1v2`	The item requires features in `MTLFeatureSet_iOS_GPUFamily1_v2`.
`metal1v3`	The item features in `MTLFeatureSet_iOS_GPUFamily1_v3`.
`metal2v2`	The item requires features in `MTLFeatureSet_iOS_GPUFamily2_v2` and `MTLFeatureSet_tvOS_GPUFamily1_v1`.
`metal2v3`	The item requires features in `MTLFeatureSet_iOS_GPUFamily2_v3` and `MTLFeatureSet_tvOS_GPUFamily1_v2`.
`metal3v1`	The item requires features in `MTLFeatureSet_iOS_GPUFamily3_v1`.
`metal3v2`	The item requires features in `MTLFeatureSet_iOS_GPUFamily3_v2`.
`metal4v1`	The item requires features in `iOS_GPUFamily4_v1`.

idiom

The device family (Table 18-6).

**Table 18-6**`idiom` values
Value	Description
`appLauncher`	An image shown app launcher on watchOS
`companionSettings`	An image for the Apple Watch Settings app
`ios-marketing`	An image for the App Store icon
`iphone`	The image is for iPhone devices.
`ipad`	The image is for iPad devices.
`mac`	The image is for Mac computers.
`notificationCenter`	An image for the notification center on watchOS.
`quickLook`	An image used for a long look on watchOS.
`tv`	The image is for Apple TV.
`universal`	The image works on any device and platform.
`watch`	The image is for the Apple Watch devices.
`watch-marketing`	An image for the App Store icon.
Tag not included	Same as specifying `universal`.

language-direction

The horizontal display direction of the image for left-to-right and right-to-left languages. (Table 18-7).

**Table 18-7**`language-direction` values
Value	Description
Tag not included	The image has a fixed horizontal orientation and will display in the same direction.
`left-to-right`	The image is used for display in left-to-right languages. The image is mirrored in right-to-left languages unless a right-to-left version of the image is provided.
`right-to-left`	The image is used for display in right-to-left languages. The image is mirrored in left-to-right languages unless a left-to-right version of the image is provided.

memory

The minimum device memory configuration required by the data item (Table 18-8).

**Table 18-8**`memory` values
Value	Description
Tag not included	The data item works on any device.
`1GB`	The device needs at least a 1GB memory configuration.
`2GB`	The device needs at least a 2GB memory configuration.
`3GB`	The device needs at least a 3GB memory configuration.
`4GB`	The device needs at least a 4GB device memory configuration.

scale

The targeted display scale for the image (Table 18-9).

**Table 18-9**`scale` values
Value	Description
Tag not included	The image is for any display scale and should point to a `.pdf` file.
`1x`	Targeted for unscaled displays.
`2x`	Targeted for Retina displays.
`3x`	Targeted for Retina displays with higher density such as those on the iPhone 6 Plus.

screen-width

The screen width for the Apple Watch (Table 18-10).

**Table 18-10**`screen-width` values
Value	Description
Tag not included	The image is for any Apple Watch screen.
`<=145`	Screen width for the 42mm Apple Watch screen.
`>145`	Screen width for the 38mm Apple Watch screen.

template-rendering-intent

Indicates if the image is a renderable image or is a template for. (Table 18-11).

**Table 18-11**`template-rendering-intent` values
Value	Description
Tag not included	If the name of the image ends in "Template", use the image as a template, otherwise render it as the original image.
`original`	Render as the original image.
`template`	Use the image as a template for visual effects such as replacing colors.

width-class

The size class for the image width (Table 18-12).

**Table 18-12**`width-class` values
Value	Description
Tag not included	The image width is for the `any` size class.
`compact`	The image width is for the `compact` size class.
`regular`	The image width is for the `regular` size class.

height-class

The size class for the image height (Table 18-13).

**Table 18-13**`height-class` values
Value	Description
Tag not included	The image height is for the `any` size class.
`compact`	The image height is for the `compact` size class.
`regular`	The image height is for the `regular` size class.

resizing mode

The mode for a sliced resizable image (Table 18-14).

**Table 18-14**`resizing mode` values
Value	Description
Tag not included	The entire image is resized.
`3-part-horizontal`	The image is divided into three horizontal parts. The outer portions are fixed-width. The central portion resizes in the horizontal dimension.
`3-part-vertical`	The image is divided into three vertical parts. The outer portions are fixed-height. The central portion resizes in the vertical dimension.
`9-part`	The image is divided into nine parts. There is a central area that resizes in the horizontal and vertical dimensions, fixed-width vertical caps at the left and right of the central area, fixed-height caps at the top and bottom of the central area, and four fixed-size corner parts.

center mode

The resizing mode of the central area of a resizing image (Table 18-15).

**Table 18-15**`center mode` values
Value	Description
Tag not included
`tile`	The central area is tiled to fill the available size.
`stretch`	The central area is stretched to fill the available size.

Sample Contents.json File

        {
   "images" : [
      {
         "idiom" : "universal",
         "scale" : "1x"
      },
      {
         "graphics-feature-set" : "metal1v2",
         "idiom" : "universal",
         "filename" : "Llama.png"
         "scale" : "2x"
      },
      {
         "graphics-feature-set" : "metal2v2",
         "idiom" : "universal",
         "memory" : "2GB",
         "scale" : "3x"
      }
   ],
   "info" : {
      "author" : "com.developerName",
      "version" : 1
   },
   "properties" : {
      "on-demand-resources : [
         "llama",
         "mountain"
      ]
   }
}

      

Icon Set Type

Image Stack Type