https://github.com/rs/SDURLCache

URLCache subclass with on-disk cache support on iPhone/iPad
https://github.com/rs/SDURLCache

Last synced: about 2 months ago
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URLCache subclass with on-disk cache support on iPhone/iPad

• Host: GitHub
• URL: https://github.com/rs/SDURLCache
• Owner: rs
• License: mit
• Created: 2010-03-16T09:16:25.000Z (over 14 years ago)
• Default Branch: master
• Last Pushed: 2017-04-03T04:56:56.000Z (over 7 years ago)
• Last Synced: 2024-07-20T11:06:36.108Z (2 months ago)
• Language: Objective-C
• Homepage:
• Size: 57.6 KB
• Stars: 798
• Watchers: 39
• Forks: 248
• Open Issues: 20
• Metadata Files:
  • Readme: README.md

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README

        
On iPhone OS, Apple did remove on-disk cache support for unknown reason. Some will say it's to save

flash-drive life, others will arg it's to save disk capacity. As it is explained in the

NSURLCacheStoragePolicy, the NSURLCacheStorageAllowed constant is always treated as

NSURLCacheStorageAllowedInMemoryOnly and there is no way to force it back, the code is certainly

gone on this platform. For whatever reason Apple removed this feature, you may be interested by

having on-disk HTTP request caching in your application. SDURLCache gives back this feature to this

iPhone OS for you.

To use it, you just have create an instance, replace the default shared NSURLCache with it and

that's it, you instantly give on-disk HTTP request caching capability to your application.

    SDURLCache *urlCache = [[SDURLCache alloc] initWithMemoryCapacity:1024*1024   // 1MB mem cache

                                                         diskCapacity:1024*1024*5 // 5MB disk cache

                                                             diskPath:[SDURLCache defaultCachePath]];

    [NSURLCache setSharedURLCache:urlCache];

    [urlCache release];

To save flash drive, SDURLCache doesn't cache on disk responses if cache expiration delay is lower

than 5 minutes by default. You can change this behavior by changing the `minCacheInterval` property.

Cache eviction is done automatically when disk capacity is reached in a periodic maintenance

thread. All disk write operations are done in a separated thread so they can't block the main run

loop.

To control the caching behavior, use the `NSURLRequest`'s `cachePolicy` property. If you want a

response not to be cached on disk but still in memory, you can implement the `NSURLConnection`

`connection:willCacheResponse:` delegate method and change the `NSURLCachedResponse` `storagePolicy`

property to `NSURLCacheStorageAllowedInMemoryOnly`. See example below:

    - (NSCachedURLResponse *)connection:(NSURLConnection *)connection

                      willCacheResponse:(NSCachedURLResponse *)cachedResponse

    {

        NSCachedURLResponse *memOnlyCachedResponse =

            [[NSCachedURLResponse alloc] initWithResponse:cachedResponse.response

                                                     data:cachedResponse.data

                                                 userInfo:cachedResponse.userInfo

                                            storagePolicy:NSURLCacheStorageAllowedInMemoryOnly];

        return [memOnlyCachedResponse autorelease];

    }