UIImageView category to download images asynchronously using the cache policy of the HTTP server if it is reachable otherwise look up for the image resource in the local HTTP cache. Depends on AFNetworking UIImageView category and Reachability components. #utils #image #UIImageView #cache #http #download

UIImageView+OfflineCache.h

#import <UIKit/UIKit.h>

@interface UIImageView (OfflineCache)

-(void)setImageCachedWithURL:(NSURL*)url
            placeholderImage:(UIImage *)placeholderImage
                     success:(void (^)(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image))success
                     failure:(void (^)(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error))failure;

@end

UIImageView+OfflineCache.m

#import "UIImageView+OfflineCache.h"
#import "UIImageView+AFNetworking.h"
#import "Reachability.h"

@implementation UIImageView (OfflineCache)

-(void)setImageCachedWithURL:(NSURL*)url
            placeholderImage:(UIImage *)placeholderImage
                     success:(void (^)(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image))success
                     failure:(void (^)(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error))failure
{
    NSURLRequestCachePolicy cachePolicy;
    Reachability* currentReachability = [Reachability reachabilityForInternetConnection];
    
    if (currentReachability.currentReachabilityStatus != NotReachable) {
        cachePolicy = NSURLRequestUseProtocolCachePolicy;
    } else {
        cachePolicy = NSURLRequestReturnCacheDataDontLoad;
    }
    
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url cachePolicy:cachePolicy timeoutInterval:60];
    [request setHTTPShouldHandleCookies:NO];
    [request addValue:@"image/*" forHTTPHeaderField:@"Accept"];
    
    [self setImageWithURLRequest:request
                placeholderImage:placeholderImage
                         success:success
                         failure:failure];
}

@end