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LRImageManager

LRImageManager is a full-featured Objective-C image library.

It supports:

• Extremely efficient asynchronous image downloading using NSOperation and NSURLConnection.
• Image request cancellation and auto retry.
• Two memory cache types via NSCache and NSDictionary.
• Asynchronous disk cache using GCD (with automatic cache storage cleanup based on directory maximum size or time).
• UIImage category for image resizing and decompressing.
• Images with the same URL and size are guaranteed to be downloaded only once.
• UIImageView category for easy asynchronous image download (possibility to have a subtle fade animation when setting the image).

Installation

1. Using CocoaPods

Add LRImageManager to your Podfile:

platform :ios, "6.0"
pod 'LRImageManager'

Run the following command:

pod install

2. Manually

Clone the project or add it as a submodule. Drag the whole LRImageManager folder to your project (also Reachability.h/m files under the Vendor/Reachability folder after initializing the submodule).

Usage

To download an image, you only have to use the following method from LRImageManager:

- (void)imageFromURL:(NSURL *)url
                size:(CGSize)size
 cacheStorageOptions:(LRCacheStorageOptions)cacheStorageOptions
   completionHandler:(LRImageCompletionHandler)completionHandler;

Just specify the URL to download from and the size you want the image to be resized to (normally, the UIImageView container size). In case of not needing to resize, you can always use CGSizeZero.

The resulting image will be downloaded from the given URL, resized to the specified size, decompressed and, depending on the storageOptions parameter, saved in memory (NSCache or NSDictionary) and disk.

LRCacheStorageOptions is defined as follows in LRImageCache.h.

typedef NS_OPTIONS(NSUInteger, LRCacheStorageOptions)
{
    LRCacheStorageOptionsNone         = 0,
    LRCacheStorageOptionsNSDictionary = 1 << 0,
    LRCacheStorageOptionsNSCache      = 1 << 1,
    LRCacheStorageOptionsDiskCache    = 1 << 2,
};

The option to save it in a NSDictionary instead of NSCache is very handy for the cases when you can't afford some images to be flushed from memory (of course they will be gone in case of memory warnings). You can't save both in NSCache and NSDictionary.

LRImageCompletionHandler contains the downloaded image and an error if any issue arises.

typedef void (^LRImageCompletionHandler)(UIImage *image, NSError *error);

You can always cancel a specific request or every ongoing request:

- (void)cancelImageRequestFromURL:(NSURL *)url size:(CGSize)size;
- (void)cancelAllRequests;

You can inject LRImageManager an image cache implementation of your own (maybe a wrapper around TMCache) conforming to the LRImageCache protocol. If you don't do so, an proper LRImageCache instance will be created for you. This cache is handled automatically by LRImageManager. In case you still want to use it for your own purposes, you can easily save and restore images:

- (UIImage *)memCachedImageForKey:(NSString *)key;

- (UIImage *)memCachedImageForURL:(NSURL *)url size:(CGSize)size;

- (void)diskCachedImageForKey:(NSString *)key
 	          completionBlock:(void (^)(UIImage *image))completionBlock;

- (void)diskCachedImageForURL:(NSURL *)url
		                 size:(CGSize)size
	          completionBlock:(void (^)(UIImage *image))completionBlock;

- (void)cacheImage:(UIImage *)image
	       withKey:(NSString *)key
    storageOptinos:(LRCacheStorageOptions)storageOptions;

- (void)cacheImage:(UIImage *)image
           withURL:(NSURL *)url
              size:(CGSize)size
    storageOptions:(LRCacheStorageOptions)storageOptions;

To easily download an image and assign it to a UIImageView container, there's a handy category UIImageView+LRNetworking for that very purpose. Just set the URL, placeholder, size and storageOptions and you are good to go. There's also a method to cancel the current image request for that UIImageView.

- (void)lr_setImageWithURL:(NSURL *)url
          placeholderImage:(UIImage *)placeholderImage
                      size:(CGSize)size
       cacheStorageOptions:(LRCacheStorageOptions)cacheStorageOptions;

- (void)lr_cancelImageOperation;

You can even choose among different animations when the image is set:

typedef NS_ENUM(NSUInteger, LRImageViewAnimationType)
{
    LRImageViewAnimationTypeNone,
    LRImageViewAnimationTypeCrossDissolve,
    LRImageViewAnimationTypeFlipFromLeft,
    LRImageViewAnimationTypeFlipFromRight,
    LRImageViewAnimationTypeFlipFromTop,
    LRImageViewAnimationTypeFlipFromBottom,
    LRImageViewAnimationTypeCurlUp,
    LRImageViewAnimationTypeCurlDown,
};

LRImageViewAnimationTypeCrossDissolve will be used by default. You can changelr_animationTime to tweak the animation time.

You also have the chance to set an activity indicator view via lr_activityIndicator, a block to make fancy animations to the downloaded image in the background (apply a grayscale effect for instance), lr_postProcessingBlock, or have a block called when the image has been set, lr_completionHandler.

Requirements

LRImageManager requires both iOS 6.0 and ARC.

You can still use LRImageManager in your non-arc project. Just set -fobjc-arc compiler flag in every source file.

Example

The best example for this library is a fully-featured TV Show Tracker app developed as the example of the LRTVDBAPIClient.

Contact

LRImageManager was created by Luis Recuenco: @luisrecuenco.

Contributing

If you want to contribute to the project just follow this steps:

1. Fork the repository.
2. Clone your fork to your local machine.
3. Create your feature branch.
4. Commit your changes, push to your fork and submit a pull request.

License

LRImageManager is available under the MIT license. See the LICENSE file for more info.