Web Image

    Build Status Pod Version Pod Platform Pod License Dependency Status Reference Status Carthage compatible

    This library provides a category for UIImageView with support for remote images coming from the web.

    It provides:

    • An UIImageView category adding web image and cache management to the Cocoa Touch framework
    • An asynchronous image downloader
    • An asynchronous memory + disk image caching with automatic cache expiration handling
    • Animated GIF support
    • WebP format support
    • A background image decompression
    • A guarantee that the same URL won't be downloaded several times
    • A guarantee that bogus URLs won't be retried again and again
    • A guarantee that main thread will never be blocked
    • Performances!
    • Use GCD and ARC
    • Arm64 support

    NOTE: Version 3.8 of SDWebImage requires iOS 7 or later (because of NSURLSession). Versions 3.7 to 3.0 requires iOS 5.1.1. If you need iOS < 5.0 support, please use the last 2.0 version.

    How is SDWebImage better than X?

    Who Uses It

    Find out who uses SDWebImage and add your app to the list.

    How To Use

    API documentation is available at CocoaDocs - SDWebImage

    Using UIImageView+WebCache category with UITableView

    Just #import the UIImageView+WebCache.h header, and call the sd_setImageWithURL:placeholderImage: method from the tableView:cellForRowAtIndexPath: UITableViewDataSource method. Everything will be handled for you, from async downloads to caching management.

    #import <SDWebImage/UIImageView+WebCache.h>
    - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
        static NSString *MyIdentifier = @"MyIdentifier";
        UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:MyIdentifier];
        if (cell == nil) {
            cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
                                           reuseIdentifier:MyIdentifier] autorelease];
        // Here we use the new provided sd_setImageWithURL: method to load the web image
        [cell.imageView sd_setImageWithURL:[NSURL URLWithString:@""]
                          placeholderImage:[UIImage imageNamed:@"placeholder.png"]];
        cell.textLabel.text = @"My Text";
        return cell;

    Using blocks

    With blocks, you can be notified about the image download progress and whenever the image retrieval has completed with success or not:

    // Here we use the new provided sd_setImageWithURL: method to load the web image
    [cell.imageView sd_setImageWithURL:[NSURL URLWithString:@""]
                          placeholderImage:[UIImage imageNamed:@"placeholder.png"]
                                 completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL) {
                                    ... completion code here ...

    Note: neither your success nor failure block will be call if your image request is canceled before completion.

    Using SDWebImageManager

    The SDWebImageManager is the class behind the UIImageView+WebCache category. It ties the asynchronous downloader with the image cache store. You can use this class directly to benefit from web image downloading with caching in another context than a UIView (ie: with Cocoa).

    Here is a simple example of how to use SDWebImageManager:

    SDWebImageManager *manager = [SDWebImageManager sharedManager];
    [manager downloadImageWithURL:imageURL
                         progress:^(NSInteger receivedSize, NSInteger expectedSize) {
                             // progression tracking code
                         completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, BOOL finished, NSURL *imageURL) {
                             if (image) {
                                 // do something with image

    Using Asynchronous Image Downloader Independently

    It's also possible to use the async image downloader independently:

    SDWebImageDownloader *downloader = [SDWebImageDownloader sharedDownloader];
    [downloader downloadImageWithURL:imageURL
                            progress:^(NSInteger receivedSize, NSInteger expectedSize) {
                                // progression tracking code
                           completed:^(UIImage *image, NSData *data, NSError *error, BOOL finished) {
                                if (image && finished) {
                                    // do something with image

    Using Asynchronous Image Caching Independently

    It is also possible to use the async based image cache store independently. SDImageCache maintains a memory cache and an optional disk cache. Disk cache write operations are performed asynchronous so it doesn't add unnecessary latency to the UI.

    The SDImageCache class provides a singleton instance for convenience but you can create your own instance if you want to create separated cache namespace.

    To lookup the cache, you use the queryDiskCacheForKey:done: method. If the method returns nil, it means the cache doesn't currently own the image. You are thus responsible for generating and caching it. The cache key is an application unique identifier for the image to cache. It is generally the absolute URL of the image.

    SDImageCache *imageCache = [[SDImageCache alloc] initWithNamespace:@"myNamespace"];
    [imageCache queryDiskCacheForKey:myCacheKey done:^(UIImage *image) {
        // image is not nil if image was found

    By default SDImageCache will lookup the disk cache if an image can't be found in the memory cache. You can prevent this from happening by calling the alternative method imageFromMemoryCacheForKey:.

    To store an image into the cache, you use the storeImage:forKey: method:

    [[SDImageCache sharedImageCache] storeImage:myImage forKey:myCacheKey];

    By default, the image will be stored in memory cache as well as on disk cache (asynchronously). If you want only the memory cache, use the alternative method storeImage:forKey:toDisk: with a negative third argument.

    Using cache key filter

    Sometime, you may not want to use the image URL as cache key because part of the URL is dynamic (i.e.: for access control purpose). SDWebImageManager provides a way to set a cache key filter that takes the NSURL as input, and output a cache key NSString.

    The following example sets a filter in the application delegate that will remove any query-string from the URL before to use it as a cache key:

    - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
        SDWebImageManager.sharedManager.cacheKeyFilter = ^(NSURL *url) {
            url = [[NSURL alloc] initWithScheme:url.scheme path:url.path];
            return [url absoluteString];
        // Your app init code...
        return YES;

    Common Problems

    Using dynamic image size with UITableViewCell

    UITableView determines the size of the image by the first image set for a cell. If your remote images don't have the same size as your placeholder image, you may experience strange anamorphic scaling issue. The following article gives a way to workaround this issue:

    Handle image refresh

    SDWebImage does very aggressive caching by default. It ignores all kind of caching control header returned by the HTTP server and cache the returned images with no time restriction. It implies your images URLs are static URLs pointing to images that never change. If the pointed image happen to change, some parts of the URL should change accordingly.

    If you don't control the image server you're using, you may not be able to change the URL when its content is updated. This is the case for Facebook avatar URLs for instance. In such case, you may use the SDWebImageRefreshCached flag. This will slightly degrade the performance but will respect the HTTP caching control headers:

    [imageView sd_setImageWithURL:[NSURL URLWithString:@""]
                     placeholderImage:[UIImage imageNamed:@"avatar-placeholder.png"]

    Add a progress indicator

    See this category:


    There are three ways to use SDWebImage in your project:

    • using CocoaPods
    • copying all the files into your project
    • importing the project as a static library

    Installation with CocoaPods

    CocoaPods 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 section for more details.


    platform :ios, '7.0'
    pod 'SDWebImage', '~>3.8'

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

    platform :ios, '8.0'


    There are 3 subspecs available now: Core, MapKit and WebP (this means you can install only some of the SDWebImage modules. By default, you get just Core, so if you need WebP, you need to specify it).

    Podfile example:

    pod 'SDWebImage/WebP'

    Installation with Carthage (iOS 8+)

    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


    github "rs/SDWebImage"



    If you installed using CocoaPods:

    import SDWebImage

    If you installed manually:

    import WebImage


    @import WebImage;

    Installation by cloning the repository

    In order to gain access to all the files from the repository, you should clone it.

    git clone --recursive

    Add the SDWebImage project to your project

    • Download and unzip the last version of the framework from the download page
    • Right-click on the project navigator and select "Add Files to "Your Project":
    • In the dialog, select SDWebImage.framework:
    • Check the "Copy items into destination group's folder (if needed)" checkbox

    Add dependencies

    • In you application project app’s target settings, find the "Build Phases" section and open the "Link Binary With Libraries" block:
    • Click the "+" button again and select the "ImageIO.framework", this is needed by the progressive download feature:

    Add Linker Flag

    Open the "Build Settings" tab, in the "Linking" section, locate the "Other Linker Flags" setting and add the "-ObjC" flag:

    Other Linker Flags

    Alternatively, if this causes compilation problems with frameworks that extend optional libraries, such as Parse, RestKit or opencv2, instead of the -ObjC flag use:

    -force_load SDWebImage.framework/Versions/Current/SDWebImage

    If you're using Cocoa Pods and have any frameworks that extend optional libraries, such as Parsen RestKit or opencv2, instead of the -ObjC flag use:

    -force_load $(TARGET_BUILD_DIR)/libPods.a

    and this:


    Import headers in your source files

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

    #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.

    Future Enhancements

    • LRU memory cache cleanup instead of reset on memory warning


    All source code is licensed under the MIT License.


    Asynchronous image downloader with cache support as a UIImageView category

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    发行版本 104

    5.12.2 - 5.12 Patch


    贡献者 270



    • Objective-C 96.9 %
    • C 2.6 %
    • Ruby 0.3 %
    • Swift 0.1 %