GDRSImageCache is a minimalistic caching and image resizing library for iOS. Given an URL it retrieves the image on a background thread and it caches it in memory.

GDRSImageCache can be provided with a filtering block which can be used to resize and mask the images obtained from the URL before caching. This unique feature provides fast image rendering because the resizing and masking of the image is done on a background thread only once per image before caching. Thus this library is particularly well suited to be used with table and collection views, as it provides smooth scrolling.

###Using COCOAPODS

From the COCOAPODS website:

CocoaPods is the dependency manager for Objective-C projects. It has thousands of libraries and can help you scale your projects elegantly.

####New to COCOAPODS:

If you do not have COCOAPODS installed, follow these steps to install COCOAPODS and GDRSImageCache:

1. Instal COCOAPODS as described in the "INSTALL" section of http://cocoapods.org.
2. Follow the instructions under the "GET STARTED" section from the same webpage (http://cocoapods.org).
3. In the Podfile instead of the lines pod 'JSONKit', '~> 1.4' and pod 'Reachability', '~> 3.0' write pod 'GDRSImageCache', '~> 1.0'.

Your pod file should now look like this:

platform :ios, '7.0'
pod 'GDRSImageCache',	'~> 1.0'

Of course the ios versions can be less than 7.0. GDRSImageCache suports ios version of 5.0 and above.

####Using COCOAPODS already:

If you have already installed COCOAPODS just add following line to your Podfile

pod 'GDRSImageCache',	'~> 1.0'

GDRSImageCache suports ios versions of 5.0 and above.

###Manual installation

Drag and drop following four files from the GDRSImageCache directory into Xcode in the Project Navigator:

• GDRSImageCache.h
• GDRSImageCache.m
• UIImage+GDRSResizing.h
• UIImage+GDRSResizing.m

Also make sure that they are added to your target.

A typical usage of GDRSImageCache is as shown below:

UIImageView *anImageView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 40, 40)];

// create the cache
GDRSImageCache *cache = [[GDRSImageCache alloc] initWithCachedImageFilter:^UIImage *(UIImage *sourceImage) {
	
	// resize the image to the image view size and round the image corners; 
	// this is called by the cache on a background thread
	return [sourceImage gdrs_resizedImageToAspectFitSize:anImageView.bounds.size cornerRadius:10];
	
}];

// set the default image, which will be returned from
// fetchImageWithURL:completionHandler: if an image coresponding to the
// requested url is not cached yet.
cache.defaultImage = [UIImage imageNamed:<#place holder image name#>];


NSURL *imageUrl = <#an url to a image#>;

// fetch an image; the call returns imidiatly and the callback handler
// is called when the image is fetched over the network
anImageView.image = [cache fetchImageWithURL:imageUrl completionHandler:^(UIImage *image, NSError *error) {
	anImageView.image = image;
}];

To use the GDRSImageCache class by it's self you need #import <GDRSImageCache/GDRSImageCache.h>. For the resizing methods of UIImage (e.g. gdrs_resizedImageToAspectFitSize:) you need #import <GDRSImageCache/UIImage+GDRSResizing.h>.