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Mobile Safari: Offline Application Cache Limit

By Rien | February 22nd, 2011 | 4 Comments

Recently we’ve launched our new mobile galleries. I’ve experimented in an earlier stage with Mobile Safari’s Offline Application cache with a very simple idea: to give the user the option

to locally store an image gallery for offline use. Great in combination with the ‘Add to Homescreen’ functionality that the buy cheap cialis online iPhone an iPad provides.

Implementation was simple using the Apple Developer docs and the great tutorials here, all worked great. Except when downloading more than 5MB of data, the process simply hangs. Damn, that’s not a lot. Apple’s documentation does not say anything about a caching limit. Posted a question about a caching limit on StackOverflow, but found no definitive answer on the cache limit of Mobile Safari’s Offline Application cache.

After sending an e-mail to Apple Developer support I did not get a definite answer on the 5mb limit, but “that there is no supported way to achieve the desired functionality given the currently shipping system configurations” .

My e-mail:

Name: Rien Swagerman
E-mail: rien@viewbook.com
Company: viewbook.com
iPhone Developer Program
viagra for sale

Team ID: none
Follow-Up ID (if referring or responding to an open issue): none

DESCRIPTION OF PROBLEM
When using the manifest file for Safari Offline Application Cache there seems to be a limit of 5mb to cache (iPad and iPhone). Is this correct?

We want to provide offline image galleries to our users (on the iPad and iPhone), synced with their viewbook.com galleries, but this needs more data storage than 5mb. Is this possible (in the near future)?

For us it is a strategic choice to either use Safari, or if not possible create a native app for the iPad and iPhone.

STEPS TO REPRODUCE
Use manifest file that loads more than 5mb of files.

NOTES AND ATTACHMENTS
None.

———————————

Thanks,
Rien swagerman.

Apple’s response:

Hello Rien,

Thank you for contacting Apple Developer Technical Support (DTS). Our engineers have reviewed your request and have concluded that there is no supported way to achieve the desired functionality given the currently shipping system configurations.

If you would like for Apple to consider adding support for such features in the future, please submit an enhancement request via the Bug Reporter tool at <http://bugreport.apple.com>.

Thank you for taking the time to file this report. We truly appreciate your help in discovering and isolating issues.

Best Regards,

Vanaja Pasumarthi
Apple Developer Support
Worldwide Developer Relations

Posted by: Rien / rien@viewbook.com

Interesting. I am able (as of the latest release) to get this working on my iPhone 4 but NOT on the iPad 1 even though both are running the latest iOS.

On my iPad I am seeing the same behavior you note (it just “hangs”) whereas my iPhone sitting right beside it progresses all the way to the end and asks if I want to increase the storage.

I was just about to begin writing abotu this same behavior. Have you had any progress with the issue since February?

Comment by Matt Ray — March 24, 2011 @ 2:31 pm

So the iPhone4 presents a dialogue and asks you if you want to increase the storage for that site? Wow. How much data can you save on your iPhone4 with one manifest file/request? Over 5MB?

Interesting what the iPad2 will do.

I did not look into it recently, please keep me/us updated on your findings. Would be good to know if there’s still a storage limit.

Thanks for the feedback Matt.

Comment by Rien — March 24, 2011 @ 7:44 pm

You are correct. The newest flavors (not sure when it stated) of iOS 4 now prompt you to increase the storage. There appears to be a strange bug (either on the iOS side or mine, more likely mine) that causes it to generate an error on the applciation cache object if you authorize the cache increase AND does not actually save the content to cache (only on refresh does it commit it to the new, enlarged storage space).

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