SDWebImage/README.md

<p align="center" >
  <img src="https://raw.githubusercontent.com/rs/SDWebImage/master/SDWebImage_logo.png" title="SDWebImage logo" float=left>
</p>


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This library provides an async image downloader with cache support. For convenience, we added categories for UI elements like `UIImageView`, `UIButton`, `MKAnnotationView`.

## Features

- [x] Categories for `UIImageView`, `UIButton`, `MKAnnotationView` adding web image and cache management
- [x] An asynchronous image downloader
- [x] An asynchronous memory + disk image caching with automatic cache expiration handling
- [x] A background image decompression
- [x] Improved [support for animated images](https://github.com/rs/SDWebImage/wiki/Advanced-Usage#animated-image-50)
- [x] [Customizable and composable transformations](https://github.com/rs/SDWebImage/wiki/Advanced-Usage#transformer-50) can be applied to the images right after download
- [x] [Custom cache control](https://github.com/rs/SDWebImage/wiki/Advanced-Usage#custom-cache-50)
- [x] Expand the image loading capabilites by adding your [own custom loaders](https://github.com/rs/SDWebImage/wiki/Advanced-Usage#custom-loader-50) or using prebuilt loaders like [FLAnimatedImage plugin](https://github.com/SDWebImage/SDWebImageFLPlugin) or [Photos Library plugin](https://github.com/SDWebImage/SDWebImagePhotosPlugin)
- [x] [Loading indicators](https://github.com/rs/SDWebImage/wiki/How-to-use#use-view-indicator-50)
- [x] A guarantee that the same URL won't be downloaded several times
- [x] A guarantee that bogus URLs won't be retried again and again
- [x] A guarantee that main thread will never be blocked
- [x] Performances!
- [x] Use GCD and ARC

## Supported Image Formats

- Image formats supported by UIImage (JPEG, PNG, ...), including GIF
- WebP format, including animated WebP (use the [SDWebImageWebPCoder](https://github.com/SDWebImage/SDWebImageWebPCoder) project)

## Additional modules

In order to keep SDWebImage focused and limited to the core features, but also allow extensibility and custom behaviors, during the 5.0 refactoring we focused on modularizing the library.
As such, we have moved/built new modules to [SDWebImage org](https://github.com/SDWebImage).

#### Coders for additional image formats
- [SDWebImageWebPCoder](https://github.com/SDWebImage/SDWebImageWebPCoder) - coder for WebP image format. Based on [libwebp](https://chromium.googlesource.com/webm/libwebp)
- [SDWebImageHEIFCoder](https://github.com/SDWebImage/SDWebImageHEIFCoder) - coder to support HEIF image without Apple's `Image/IO framework`
- [SDWebImageAPNGCoder](https://github.com/SDWebImage/SDWebImageAPNGCoder) - coder for APNG format (animated PNG)
- [SDWebImageBPGCoder](https://github.com/SDWebImage/SDWebImageBPGCoder) - coder for BPG format

#### Loaders
- [SDWebImagePhotosPlugin](https://github.com/SDWebImage/SDWebImagePhotosPlugin) - plugin to support loading images from Photos (using `Photos.framework`) 

#### Integration with 3rd party libraries
- [SDWebImageFLPlugin](https://github.com/SDWebImage/SDWebImageFLPlugin) - plugin to support [FLAnimatedImage](https://github.com/Flipboard/FLAnimatedImage) as the engine for animated GIFs
- [SDWebImageYYPlugin](https://github.com/SDWebImage/SDWebImageYYPlugin) - plugin to integrate [YYImage](https://github.com/ibireme/YYImage) & [YYCache](https://github.com/ibireme/YYCache) for image rendering & caching
- [SDWebImageProgressiveJPEGDemo](https://github.com/SDWebImage/SDWebImageProgressiveJPEGDemo) - demo project for using `SDWebImage` + [Concorde library](https://github.com/contentful-labs/Concorde) for Progressive JPEG decoding

#### Make our lives easier
- [libwebp-Xcode](https://github.com/SDWebImage/libwebp-Xcode) - A wrapper for [libwebp](https://chromium.googlesource.com/webm/libwebp) + an Xcode project.

You can use those directly, or create similar components of your own.

## Requirements

- iOS 8.0 or later
- tvOS 9.0 or later
- watchOS 2.0 or later
- macOS 10.10 or later
- Xcode 9.0 or later

#### Backwards compatibility

- For iOS 7, macOS 10.9 or Xcode < 8, use [any 4.x version up to 4.3.3](https://github.com/rs/SDWebImage/releases/tag/4.3.3)
- For macOS 10.8, use [any 4.x version up to 4.3.0](https://github.com/rs/SDWebImage/releases/tag/4.3.0)
- For iOS 5 and 6, use [any 3.x version up to 3.7.6](https://github.com/rs/SDWebImage/tag/3.7.6)
- For iOS < 5.0, please use the last [2.0 version](https://github.com/rs/SDWebImage/tree/2.0-compat).

## Getting Started

- Read this Readme doc
- Read the [How to use section](https://github.com/rs/SDWebImage#how-to-use)
- Read the [Documentation @ CocoaDocs](http://cocoadocs.org/docsets/SDWebImage/)
- Try the example by downloading the project from Github or even easier using CocoaPods try `pod try SDWebImage`
- Read the [Installation Guide](https://github.com/rs/SDWebImage/wiki/Installation-Guide)
- Read the [SDWebImage 5.0 Migration Guide](https://raw.githubusercontent.com/rs/SDWebImage/5.x/Docs/SDWebImage-5.0-Migration-guide.md) to get an idea of the changes from 4.x to 5.x
- Read the [SDWebImage 4.0 Migration Guide](https://raw.githubusercontent.com/rs/SDWebImage/master/Docs/SDWebImage-4.0-Migration-guide.md) to get an idea of the changes from 3.x to 4.x
- Read the [Common Problems](https://github.com/rs/SDWebImage/wiki/Common-Problems) to find the solution for common problems 
- Go to the [Wiki Page](https://github.com/rs/SDWebImage/wiki) for more information such as [Advanced Usage](https://github.com/rs/SDWebImage/wiki/Advanced-Usage)

## Who Uses It
- Find out [who uses SDWebImage](https://github.com/rs/SDWebImage/wiki/Who-Uses-SDWebImage) and add your app to the list.

## Communication

- If you **need help**, use [Stack Overflow](http://stackoverflow.com/questions/tagged/sdwebimage). (Tag 'sdwebimage')
- If you'd like to **ask a general question**, use [Stack Overflow](http://stackoverflow.com/questions/tagged/sdwebimage).
- If you **found a bug**, open an issue.
- If you **have a feature request**, open an issue.
- If you **want to contribute**, read the [Contributing Guide](https://raw.githubusercontent.com/rs/SDWebImage/master/.github/CONTRIBUTING.md)

## How To Use

* Objective-C

```objective-c
#import <SDWebImage/UIImageView+WebCache.h>
...
[imageView sd_setImageWithURL:[NSURL URLWithString:@"http://www.domain.com/path/to/image.jpg"]
             placeholderImage:[UIImage imageNamed:@"placeholder.png"]];
```

* Swift

```swift
import SDWebImage

imageView.sd_setImage(with: URL(string: "http://www.domain.com/path/to/image.jpg"), placeholderImage: UIImage(named: "placeholder.png"))
```

- For details about how to use the library and clear examples, see [The detailed How to use](https://raw.githubusercontent.com/rs/SDWebImage/master/Docs/HowToUse.md)

## Animated Images (GIF) support

In 5.0, we introduced a brand new mechanism for supporting animated images. This includes animated image loading, rendering, decoding, and also supports customizations (for advanced users).
This animated image solution is available for `iOS`/`tvOS`/`macOS`. The `SDAnimatedImage` is subclass of `UIImage/NSImage`, and `SDAnimatedImageView` is subclass of `UIImageView/NSImageView`, to make them compatible with the common frameworks APIs. See [Animated Image](https://github.com/rs/SDWebImage/wiki/Advanced-Usage#animated-image-50) for more detailed information.

#### FLAnimatedImage integration has its own dedicated repo
In order to clean up things and make our core project do less things, we decided that the `FLAnimatedImage` integration does not belong here. From 5.0, this will still be available, but under a dedicated repo [SDWebImageFLPlugin](https://github.com/SDWebImage/SDWebImageFLPlugin).

## Installation

There are three ways to use SDWebImage in your project:
- using CocoaPods
- using Carthage
- by cloning the project into your repository

### Installation with CocoaPods

[CocoaPods](http://cocoapods.org/) is a dependency manager for Objective-C, which automates and simplifies the process of using 3rd-party libraries in your projects. See the [Get Started](http://cocoapods.org/#get_started) section for more details.

#### Podfile
```
platform :ios, '7.0'
pod 'SDWebImage', '~> 4.0'
```

If you are using Swift, be sure to add `use_frameworks!` and set your target to iOS 8+:
```
platform :ios, '8.0'
use_frameworks!
```

#### Subspecs

There are 2 subspecs available now: `Core` and `MapKit` (this means you can install only some of the SDWebImage modules. By default, you get just `Core`, so if you need `MapKit`, you need to specify it). 

Podfile example:
```
pod 'SDWebImage/MapKit'
```

### Installation with Carthage (iOS 8+)

[Carthage](https://github.com/Carthage/Carthage) is a lightweight dependency manager for Swift and Objective-C. It leverages CocoaTouch modules and is less invasive than CocoaPods.

To install with carthage, follow the instruction on [Carthage](https://github.com/Carthage/Carthage)

#### Cartfile
```
github "rs/SDWebImage"
```

### Installation by cloning the repository
- see [Manual install](https://raw.githubusercontent.com/rs/SDWebImage/master/Docs/ManualInstallation.md)

### Import headers in your source files

In the source files where you need to use the library, import the header file:

```objective-c
#import <SDWebImage/UIImageView+WebCache.h>
```

### Build Project

At this point your workspace should build without error. If you are having problem, post to the Issue and the
community can help you solve it.

## Author
- [Olivier Poitrey](https://github.com/rs)

## Collaborators
- [Konstantinos K.](https://github.com/mythodeia)
- [Bogdan Poplauschi](https://github.com/bpoplauschi)
- [Chester Liu](https://github.com/skyline75489)
- [DreamPiggy](https://github.com/dreampiggy)
- [Wu Zhong](https://github.com/zhongwuzw)

## Licenses

All source code is licensed under the [MIT License](https://raw.github.com/rs/SDWebImage/master/LICENSE).

## Architecture

#### High Level Diagram
<p align="center" >
    <img src="https://raw.githubusercontent.com/rs/SDWebImage/5.x/Docs/Diagrams/SDWebImageHighLevelDiagram.jpeg" title="SDWebImage high level diagram">
</p>

#### Overall Class Diagram
<p align="center" >
    <img src="https://raw.githubusercontent.com/rs/SDWebImage/5.x/Docs/Diagrams/SDWebImageClassDiagram.png" title="SDWebImage overall class diagram">
</p>

#### Top Level API Diagram
<p align="center" >
    <img src="https://raw.githubusercontent.com/rs/SDWebImage/5.x/Docs/Diagrams/SDWebImageTopLevelClassDiagram.png" title="SDWebImage top level API diagram">
</p>

#### Main Sequence Diagram
<p align="center" >
    <img src="https://raw.githubusercontent.com/rs/SDWebImage/5.x/Docs/Diagrams/SDWebImageSequenceDiagram.png" title="SDWebImage sequence diagram">
</p>

#### More detailed diagrams
- [Manager API Diagram](https://raw.githubusercontent.com/rs/SDWebImage/5.x/Docs/Diagrams/SDWebImageManagerClassDiagram.png)
- [Coders API Diagram](https://raw.githubusercontent.com/rs/SDWebImage/5.x/Docs/Diagrams/SDWebImageCodersClassDiagram.png)
- [Loader API Diagram](https://raw.githubusercontent.com/rs/SDWebImage/5.x/Docs/Diagrams/SDWebImageLoaderClassDiagram.png)
- [Cache API Diagram](https://raw.githubusercontent.com/rs/SDWebImage/5.x/Docs/Diagrams/SDWebImageCacheClassDiagram.png)