Electronic exhibition guide

Few days ago we have finished development of the Electronic exhibition guide for the Czech Architecture Week 2011 (link here). The guide is designed for iPad and uses the latest web technology - HTML5.

Primary intention was to build offline electronic guide that can be saved to iPad and can be run from Home screen via application icon. In the first point of view, it seemed like straightforward development process without any hidden problems. HTML5 specifications describes offline mode very precisely and we had previous experience with iPad online web applications too.

During development I've discovered that iOS devices (Safari web-browser) can't simply handle larger offline applications than 5 megabytes (i.e. this link). If you try to save such application user is requested to "Increase Local Storage" (see following screenshot).

This behavior occurs by steps of 10 megabytes, 25 megabytes and finally 50 megabytes. Our app has unfortunately 32 megabytes, so user should run application, accept storage increase, shutdown application and this circle 3 times more! Then the application is completely saved in local storage. It is totally annoying for any user.

I did some googling and I've found an opinion that the offline application limitation is due Apple's App Store. The opinion seems right because the limit used to be 10 megabytes and now it is only 5 megabytes.


So my recommendations are following:

• If you build non-native web application make it smaller that 5 megabytes
• If you can't compress your application under 5 megabytes develop native application that will wrap your website

We are now aware of this problem and we are planning some better solutions for the future, so follow our Twitter or subscribe RSS.