AlamofireImage

by Alamofire

Alamofire / AlamofireImage

AlamofireImage is an image component library for Alamofire

3.6K Stars 466 Forks Last release: 7 months ago (4.1.0) MIT License 520 Commits 38 Releases

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AlamofireImage

Build Status CocoaPods Compatible Carthage Compatible Platform Twitter Gitter

AlamofireImage is an image component library for Alamofire.

Features

  • [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

Requirements

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

Migration Guides

Dependencies

Communication

  • If you need to find or understand an API, check our documentation.
  • If you need help with an AlamofireImage feature, use our forum on swift.org.
  • If you'd like to discuss AlamofireImage best practices, use our forum on swift.org.
  • If you'd like to discuss a feature request, use our forum on swift.org.
  • 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.

Installation

CocoaPods

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

Podfile
:
pod 'AlamofireImage', '~> 4.1'

Carthage

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

Cartfile
:
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

swift
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

dependencies
value of your
Package.swift
.
dependencies: [
    .package(url: "https://github.com/Alamofire/AlamofireImage.git", .upToNextMajor(from: "4.1.0"))
]

Manually

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,
    cd
    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 https://github.com/Alamofire/AlamofireImage.git
  • Open the new

    AlamofireImage
    folder, and drag the
    AlamofireImage.xcodeproj
    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

    AlamofireImage.xcodeproj
    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

    AlamofireImage.xcodeproj
    folders each with two different versions of the
    AlamofireImage.framework
    nested inside a
    Products
    folder.

    It does not matter which

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

    AlamofireImage.framework
    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

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

The

AlamofireImage.framework
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.

Usage

Image Response Serializers

import Alamofire
import AlamofireImage

Alamofire.request("https://httpbin.org/image/png").responseImage { response in debugPrint(response)

print(response.request)
print(response.response)
debugPrint(response.result)

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
  • 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

addAcceptableImageContentTypes
extension on the
DataRequest
type.

UIImage Extensions

There are several

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

Inflation

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

image.af.inflate()

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

Scaling

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

// Scale image to size disregarding aspect ratio let scaledImage = image.af.imageScaled(to: size)

// Scale image to fit within specified size while maintaining aspect ratio let aspectScaledToFitImage = image.af.imageAspectScaled(toFit: size)

// Scale image to fill specified size while maintaining aspect ratio let aspectScaledToFillImage = image.af.imageAspectScaled(toFill: size)

Rounded Corners

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

let roundedImage = image.af.imageRounded(withCornerRadius: radius) let circularImage = image.af.imageRoundedIntoCircle()

Core Image Filters

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

let sepiaImage = image.af.imageFiltered(withCoreImageFilter: "CISepiaTone")

let blurredImage = image.af.imageFiltered( withCoreImageFilter: "CIGaussianBlur", parameters: ["inputRadius": 25] )

Image Filters

The

ImageFilter
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 }
}

The

filter
closure contains the operation used to create a modified version of the specified image. The
identifier
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
    CIGaussianBlur
    filter with the specified blur radius.

Each image filter is built ontop of the

UIImage
extensions.

Multi-Pass

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.

URLCache
is quite powerful and does a great job reasoning through the various cache policies and
Cache-Control
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

URLCache
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
)

The

AutoPurgingImageCache
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

ImageCache
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

The

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

let urlRequest = URLRequest(url: URL(string: "https://httpbin.org/image/png")!) 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")

Auto-Purging

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

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

It is important to set reasonable default values for the

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

Memory Warnings

The

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

Image Downloader

The

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

If you need to customize the

URLSessionConfiguration
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: "https://httpbin.org/image/jpeg")!)

downloader.download(urlRequest) { response in print(response.request) print(response.response) debugPrint(response.result)

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

}

Make sure to keep a strong reference to the

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

Applying an ImageFilter

let downloader = ImageDownloader()
let urlRequest = URLRequest(url: URL(string: "https://httpbin.org/image/jpeg")!)
let filter = AspectScaledToFillSizeCircleFilter(size: CGSize(width: 100.0, height: 100.0))

downloader.download(urlRequest, filter: filter) { response in print(response.request) print(response.response) debugPrint(response.result)

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

}

Authentication

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

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

Download Prioritization

The

ImageDownloader
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
DownloadPrioritization
enumeration allows you to specify which behavior you would prefer.
public enum DownloadPrioritization {
    case fifo, lifo
}

The

ImageDownloader
is initialized with a
.fifo
queue by default.

Image Caching

The

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

The

URLCache
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

URLSessionConfiguration
with the
urlCache
property set to
nil
and use that configuration when initializing the
ImageDownloader
.
Image Cache

The

ImageCache
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
AutoPurgingImageCache
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

URLCache
and
AutoPurgingImageCache
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

URLCache
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

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

By cancelling the request through the

ImageDownloader
using the
RequestReceipt
, 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

cancel
on the
request
in the
RequestReceipt
. 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

UIImageView
extension. Due to the powerful support of these classes, protocols and extensions, the
UIImageView
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: "https://httpbin.org/image/png")!

imageView.af.setImage(withURL: 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: "https://httpbin.org/image/png")!
let placeholderImage = UIImage(named: "placeholder")!

imageView.af.setImage(withURL: 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: "https://httpbin.org/image/png")! let placeholderImage = UIImage(named: "placeholder")!

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

imageView.af.setImage( 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

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

let url = URL(string: "https://httpbin.org/image/png")! let placeholderImage = UIImage(named: "placeholder")!

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

imageView.af.setImage( withURL: url, placeholderImage: placeholderImage, filter: filter, imageTransition: .crossDissolve(0.2) )

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

Image Downloader

The

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

If an image requires and authentication credential from the

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

Credits

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.

Donations

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.

paypal

License

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

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