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AlamofireImage is an image component library for Alamofire

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Build Status CocoaPods Compatible Carthage Compatible Platform Twitter Gitter

AlamofireImage is an image component library for Alamofire.


  • [x] Image Response Serializers
  • [x] UIImage Extensions for Inflation / Scaling / Rounding / CoreImage
  • [x] Single and Multi-Pass Image Filters
  • [x] Auto-Purging In-Memory Image Cache
  • [x] Prioritized Queue Order Image Downloading
  • [x] Authentication with URLCredential
  • [x] UIImageView Async Remote Downloads with Placeholders
  • [x] UIImageView Filters and Transitions
  • [x] Comprehensive Test Coverage
  • [x] Complete Documentation


  • iOS 10.0+ / macOS 10.12+ / tvOS 10.0+ / watchOS 3.0+
  • Xcode 11+
  • Swift 5.1+

Migration Guides



  • If you need to find or understand an API, check our documentation.
  • If you need help with an AlamofireImage feature, use our forum on
  • If you'd like to discuss AlamofireImage best practices, use our forum on
  • If you'd like to discuss a feature request, use our forum on
  • If you found a bug, open an issue and follow the guide. The more detail the better!
  • If you want to contribute, submit a pull request.



CocoaPods is a dependency manager for Cocoa projects. For usage and installation instructions, visit their website. To integrate AlamofireImage into your Xcode project using CocoaPods, specify it in your

pod 'AlamofireImage', '~> 4.1'


Carthage is a decentralized dependency manager that builds your dependencies and provides you with binary frameworks. To integrate AlamofireImage into your Xcode project using Carthage, specify it in your

github "Alamofire/AlamofireImage" ~> 4.1

Swift Package Manager

The Swift Package Manager is a tool for automating the distribution of Swift code and is integrated into the

compiler. It is in early development, but AlamofireImage does support its use on supported platforms.

Once you have your Swift package set up, adding AlamofireImage as a dependency is as easy as adding it to the

value of your
dependencies: [
    .package(url: "", .upToNextMajor(from: "4.2.0"))


If you prefer not to use either of the aforementioned dependency managers, you can integrate AlamofireImage into your project manually.

Embedded Framework

  • Open up Terminal,
    into your top-level project directory, and run the following command "if" your project is not initialized as a git repository:
$ git init
  • Add AlamofireImage as a git submodule by running the following command:
$ git submodule add
  • Open the new

    folder, and drag the
    into the Project Navigator of your application's Xcode project.

    It should appear nested underneath your application's blue project icon. Whether it is above or below all the other Xcode groups does not matter.

  • Select the

    in the Project Navigator and verify the deployment target matches that of your application target.
  • Next, select your application project in the Project Navigator (blue project icon) to navigate to the target configuration window and select the application target under the "Targets" heading in the sidebar.

  • In the tab bar at the top of that window, open the "General" panel.

  • Click on the

    button under the "Embedded Binaries" section.
  • You will see two different

    folders each with two different versions of the
    nested inside a

    It does not matter which

    folder you choose from, but it does matter whether you choose the top or bottom
  • Select the top

    for iOS and the bottom one for OS X.

    You can verify which one you selected by inspecting the build log for your project. The build target for

    will be listed as either
    AlamofireImage iOS
    AlamofireImage macOS
    AlamofireImage tvOS
    AlamofireImage watchOS
  • And that's it!


is automagically added as a target dependency, linked framework and embedded framework in a copy files build phase which is all you need to build on the simulator and a device.


Image Response Serializers

import Alamofire
import AlamofireImage

AF.request("").responseImage { response in debugPrint(response)


if case .success(let image) = response.result {
    print("image downloaded: \(image)")


The AlamofireImage response image serializers support a wide range of image types including:

  • image/png
  • image/jpeg
  • image/tiff
  • image/gif
  • image/ico
  • image/x-icon
  • image/bmp
  • image/x-bmp
  • image/x-xbitmap
  • image/x-ms-bmp
  • image/x-win-bitmap
  • image/heic
  • application/octet-stream
    (added for iOS 13 support)

If the image you are attempting to download is an invalid MIME type not in the list, you can add custom acceptable content types using the

extension on the

UIImage Extensions

There are several

extensions designed to make the common image manipulation operations as simple as possible.


let url = Bundle.main.url(forResource: "unicorn", withExtension: "png")!
let data = try! Data(contentsOf: url)
let image = UIImage(data: data, scale: UIScreen.main.scale)!

Inflating compressed image formats (such as PNG or JPEG) in a background queue can significantly improve drawing performance on the main thread.


let image = UIImage(named: "unicorn")!
let size = CGSize(width: 100.0, height: 100.0)

// Scale image to size disregarding aspect ratio let scaledImage = size)

// Scale image to fit within specified size while maintaining aspect ratio let aspectScaledToFitImage = size)

// Scale image to fill specified size while maintaining aspect ratio let aspectScaledToFillImage = size)

Rounded Corners

let image = UIImage(named: "unicorn")!
let radius: CGFloat = 20.0

let roundedImage = radius) let circularImage =

Core Image Filters

let image = UIImage(named: "unicorn")!

let sepiaImage = "CISepiaTone")

let blurredImage = withCoreImageFilter: "CIGaussianBlur", parameters: ["inputRadius": 25] )

Image Filters


protocol was designed to make it easy to apply a filter operation and cache the result after an image finished downloading. It defines two properties to facilitate this functionality.
public protocol ImageFilter {
    var filter: Image -> Image { get }
    var identifier: String { get }


closure contains the operation used to create a modified version of the specified image. The
property is a string used to uniquely identify the filter operation. This is useful when adding filtered versions of an image to a cache. All identifier properties inside AlamofireImage are implemented using protocol extensions.

Single Pass

The single pass image filters only perform a single operation on the specified image.

let image = UIImage(named: "unicorn")!
let imageFilter = RoundedCornersFilter(radius: 10.0)

let roundedImage = imageFilter.filter(image)

The current list of single pass image filters includes:

  • ScaledToSizeFilter
    - Scales an image to a specified size.
  • AspectScaledToFitSizeFilter
    - Scales an image from the center while maintaining the aspect ratio to fit within a specified size.
  • AspectScaledToFillSizeFilter
    - Scales an image from the center while maintaining the aspect ratio to fill a specified size. Any pixels that fall outside the specified size are clipped.
  • RoundedCornersFilter
    - Rounds the corners of an image to the specified radius.
  • CircleFilter
    - Rounds the corners of an image into a circle.
  • BlurFilter
    - Blurs an image using a
    filter with the specified blur radius.

Each image filter is built ontop of the



The multi-pass image filters perform multiple operations on the specified image.

let image = UIImage(named: "avatar")!
let size = CGSize(width: 100.0, height: 100.0)
let imageFilter = AspectScaledToFillSizeCircleFilter(size: size)

let avatarImage = imageFilter.filter(image)

The current list of multi-pass image filters includes:

  • ScaledToSizeWithRoundedCornersFilter
    - Scales an image to a specified size, then rounds the corners to the specified radius.
  • AspectScaledToFillSizeWithRoundedCornersFilter
    - Scales an image from the center while maintaining the aspect ratio to fit within a specified size, then rounds the corners to the specified radius.
  • ScaledToSizeCircleFilter
    - Scales an image to a specified size, then rounds the corners into a circle.
  • AspectScaledToFillSizeCircleFilter
    - Scales an image from the center while maintaining the aspect ratio to fit within a specified size, then rounds the corners into a circle.

Image Cache

Image caching can become complicated when it comes to network images.

is quite powerful and does a great job reasoning through the various cache policies and
headers. However, it is not equipped to handle caching multiple modified versions of those images.

For example, let's say you need to download an album of images. Your app needs to display both the thumbnail version as well as the full size version at various times. Due to performance issues, you want to scale down the thumbnails to a reasonable size before rendering them on-screen. You also need to apply a global CoreImage filter to the full size images when displayed. While

can easily handle storing the original downloaded image, it cannot store these different variants. What you really need is another caching layer designed to handle these different variants.
let imageCache = AutoPurgingImageCache(
    memoryCapacity: 100_000_000,
    preferredMemoryUsageAfterPurge: 60_000_000


in AlamofireImage fills the role of that additional caching layer. It is an in-memory image cache used to store images up to a given memory capacity. When the memory capacity is reached, the image cache is sorted by last access date, then the oldest image is continuously purged until the preferred memory usage after purge is met. Each time an image is accessed through the cache, the internal access date of the image is updated.

Add / Remove / Fetch Images

Interacting with the

protocol APIs is very straightforward.
let imageCache = AutoPurgingImageCache()
let avatarImage = UIImage(data: data)!

// Add imageCache.add(avatarImage, withIdentifier: "avatar")

// Fetch let cachedAvatar = imageCache.image(withIdentifier: "avatar")

// Remove imageCache.removeImage(withIdentifier: "avatar")

URL Requests


protocol extends the
protocol by adding support for
caching. This allows a
and an additional identifier to generate the unique identifier for the image in the cache.
let imageCache = AutoPurgingImageCache()

let urlRequest = URLRequest(url: URL(string: "")!) let avatarImage = UIImage(named: "avatar")!.af.imageRoundedIntoCircle()

// Add imageCache.add(avatarImage, for: urlRequest, withIdentifier: "circle")

// Fetch let cachedAvatarImage = imageCache.image(for: urlRequest, withIdentifier: "circle")

// Remove imageCache.removeImage(for: urlRequest, withIdentifier: "circle")


Each time an image is fetched from the cache, the cache internally updates the last access date for that image.

let avatar = imageCache.image(withIdentifier: "avatar")
let circularAvatar = imageCache.image(for: urlRequest, withIdentifier: "circle")

By updating the last access date for each image, the image cache can make more informed decisions about which images to purge when the memory capacity is reached. The

automatically evicts images from the cache in order from oldest last access date to newest until the memory capacity drops below the

It is important to set reasonable default values for the

when you are initializing your image cache. By default, the
equals 100 MB and the
equals 60 MB.

Memory Warnings


also listens for memory warnings from your application and will purge all images from the cache if a memory warning is observed.

Image Downloader


class is responsible for downloading images in parallel on a prioritized queue. It uses an internal Alamofire
instance to handle all the downloading and response image serialization. By default, the initialization of an
uses a default
with the most common parameter values.
let imageDownloader = ImageDownloader(
    configuration: ImageDownloader.defaultURLSessionConfiguration(),
    downloadPrioritization: .fifo,
    maximumActiveDownloads: 4,
    imageCache: AutoPurgingImageCache()

If you need to customize the

type or parameters, then simply provide your own rather than using the default.

Downloading an Image

let downloader = ImageDownloader()
let urlRequest = URLRequest(url: URL(string: "")!) { response in print(response.request) print(response.response) debugPrint(response.result)

if case .success(let image) = response.result {


Make sure to keep a strong reference to the

instance, otherwise the
closure will not be called because the
reference will go out of scope before the
closure can be called.

Applying an ImageFilter

let downloader = ImageDownloader()
let urlRequest = URLRequest(url: URL(string: "")!)
let filter = AspectScaledToFillSizeCircleFilter(size: CGSize(width: 100.0, height: 100.0)), filter: filter) { response in print(response.request) print(response.response) debugPrint(response.result)

if case .success(let image) = response.result {



If your images are behind HTTP Basic Auth, you can append the

or the
to the
instance. The credentials will be applied to all future download requests.
let downloader = ImageDownloader()
downloader.addAuthentication(user: "username", password: "password")

Download Prioritization


maintains an internal queue of pending download requests. Depending on your situation, you may want incoming downloads to be inserted at the front or the back of the queue. The
enumeration allows you to specify which behavior you would prefer.
public enum DownloadPrioritization {
    case fifo, lifo


is initialized with a
queue by default.

Image Caching


uses a combination of an
to create a very robust, high performance image caching system.


is used to cache all the original image content downloaded from the server. By default, it is initialized with a memory capacity of 20 MB and a disk capacity of 150 MB. This allows up to 150 MB of original image data to be stored on disk at any given time. While these defaults have been carefully set, it is very important to consider your application's needs and performance requirements and whether these values are right for you.

If you wish to disable this caching layer, create a custom

with the
property set to
and use that configuration when initializing the
Image Cache


is used to cache all the potentially filtered image content after it has been downloaded from the server. This allows multiple variants of the same image to also be cached, rather than having to re-apply the image filters to the original image each time it is required. By default, an
is initialized with a memory capacity of 100 MB and a preferred memory usage after purge limit of 60 MB. This allows up to 100 MB of most recently accessed filtered image content to be stored in-memory at a given time.
Setting Ideal Capacity Limits

Determining the ideal the in-memory and on-disk capacity limits of the

requires a bit of forethought. You must carefully consider your application's needs, and tailor the limits accordingly. By default, the combination of caches offers the following storage capacities:
  • 150 MB of on-disk storage (original image only)
  • 20 MB of in-memory original image data storage (original image only)
  • 100 MB of in-memory storage of filtered image content (filtered image if using filters, otherwise original image)
  • 60 MB preferred memory capacity after purge of filtered image content

If you do not use image filters, it is advised to set the memory capacity of the

to zero. Otherwise, you will be storing the original image data in both the URLCache's in-memory store as well as the AlamofireImage in-memory store.

Duplicate Downloads

Sometimes application logic can end up attempting to download an image more than once before the initial download request is complete. Most often, this results in the image being downloaded more than once. AlamofireImage handles this case elegantly by merging the duplicate downloads. The image will only be downloaded once, yet both completion handlers will be called.

Image Filter Reuse

In addition to merging duplicate downloads, AlamofireImage can also merge duplicate image filters. If two image filters with the same identifier are attached to the same download, the image filter is only executed once and both completion handlers are called with the same resulting image. This can save large amounts of time and resources for computationally expensive filters such as ones leveraging CoreImage.

Request Receipts

Sometimes it is necessary to cancel an image download for various reasons. AlamofireImage can intelligently handle cancellation logic in the

by leveraging the
type along with the
method. Each download request vends a
which can be later used to cancel the request.

By cancelling the request through the

using the
, AlamofireImage is able to determine how to best handle the cancellation. The cancelled download will always receive a cancellation error, while duplicate downloads are allowed to complete. If the download is already active, it is allowed to complete even though the completion handler will be called with a cancellation error. This greatly improves performance of table and collection views displaying large amounts of images.

It is NOT recommended to directly call

on the
in the
. Doing so can lead to issues such as duplicate downloads never being allowed to complete.

UIImageView Extension

The UIImage Extensions, Image Filters, Image Cache and Image Downloader were all designed to be flexible and standalone, yet also to provide the foundation of the

extension. Due to the powerful support of these classes, protocols and extensions, the
APIs are concise, easy to use and contain a large amount of functionality.

Setting Image with URL

Setting the image with a URL will asynchronously download the image and set it once the request is finished.

let imageView = UIImageView(frame: frame)
let url = URL(string: "")! url)

If the image is cached locally, the image is set immediately.

Placeholder Images

By specifying a placeholder image, the image view uses the placeholder image until the remote image is downloaded.

let imageView = UIImageView(frame: frame)
let url = URL(string: "")!
let placeholderImage = UIImage(named: "placeholder")! url, placeholderImage: placeholderImage)

If the remote image is cached locally, the placeholder image is never set.

Image Filters

If an image filter is specified, it is applied asynchronously after the remote image is downloaded. Once the filter execution is complete, the resulting image is set on the image view.

let imageView = UIImageView(frame: frame)

let url = URL(string: "")! let placeholderImage = UIImage(named: "placeholder")!

let filter = AspectScaledToFillSizeWithRoundedCornersFilter( size: imageView.frame.size, radius: 20.0 ) withURL: url, placeholderImage: placeholderImage, filter: filter )

If the remote image with the applied filter is cached locally, the image is set immediately.

Image Transitions

By default, there is no image transition animation when setting the image on the image view. If you wish to add a cross dissolve or flip-from-bottom animation, then specify an

with the preferred duration.
let imageView = UIImageView(frame: frame)

let url = URL(string: "")! let placeholderImage = UIImage(named: "placeholder")!

let filter = AspectScaledToFillSizeWithRoundedCornersFilter( size: imageView.frame.size, radius: 20.0 ) withURL: url, placeholderImage: placeholderImage, filter: filter, imageTransition: .crossDissolve(0.2) )

If the remote image is cached locally, the image transition is ignored.

Image Downloader


extension is powered by the default
instance. To customize cache capacities, download priorities, request cache policies, timeout durations, etc., please refer to the Image Downloader documentation.

If an image requires and authentication credential from the

extension, it can be provided as follows:
ImageDownloader.default.addAuthentication(user: "user", password: "password")


Alamofire is owned and maintained by the Alamofire Software Foundation. You can follow them on Twitter at @AlamofireSF for project updates and releases.

Security Disclosure

If you believe you have identified a security vulnerability with AlamofireImage, you should report it as soon as possible via email to [email protected] Please do not post it to a public issue tracker.


The ASF is looking to raise money to officially stay registered as a federal non-profit organization. Registering will allow us members to gain some legal protections and also allow us to put donations to use, tax free. Donating to the ASF will enable us to:

  • Pay our yearly legal fees to keep the non-profit in good status
  • Pay for our mail servers to help us stay on top of all questions and security issues
  • Potentially fund test servers to make it easier for us to test the edge cases
  • Potentially fund developers to work on one of our projects full-time

The community adoption of the ASF libraries has been amazing. We are greatly humbled by your enthusiasm around the projects, and want to continue to do everything we can to move the needle forward. With your continued support, the ASF will be able to improve its reach and also provide better legal safety for the core members. If you use any of our libraries for work, see if your employers would be interested in donating. Any amount you can donate today to help us reach our goal would be greatly appreciated.



AlamofireImage is released under the MIT license. See LICENSE for details.

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