iOS web app with offline cache and local storage

Question

I've already managed to program a webapp for personal use I'm really satisfied with. Not being something meant for public usage and distribution, I didn't want to go through the hassle of jailbreaking my device just to be able to run my own application, so I made this seamlessy looking and behaving webapp (and of course I've added it to the other apps saving it as a "Home application")

Since the start time can be a bit slow and I'm constantly pushing my data from and to a remote server, can I force the usage of html5 offline browsing (with a cache manifest) even when I am online? Also, I'm thinking of persisting the data as local storage and from time to time synch it to the server. Since I've never used html5 local storage, how much reliable is it? Can I lose my data?

Is this a viable pattern to quickly create a personal iPhone app? Thanks

Answer 1

window.localStorage.setItem('x',y);
window.localStorage.getItem('x';
window.localStorage.removeItem('x');

Lets you store, read and delete persistent data in HTML5. See https://developer.mozilla.org/en-US/docs/Web/API/Web_Storage_API/Using_the_Web_Storage_API

But note that on IOS Safari puts this data in the cache folder which on occasions gets expunged. So do plan a server sync and restore of this data if important.

Alternatively use a local SQLite database for a more persistent persistence....

Answer 2

Yes, you can force the usage.

so basically you should a very simple checking :

if(localStorage["mycontent"]!==null)
{
  // do it offline.
}else
{
  // retrieve from server database
}

For your question regarding :

Also, I'm thinking of persisting the data as local storage and from time to time synch it to the server. Since I've never used html5 local storage, how much reliable is it? Can I lose my data?

The answer is it depends. If the data is static (or can only be changed by you and not other user ) it's reliable. You also have to take note when a data can be considered expired so localstorage can be filled with refreshed data from the server.

But take note that cleaning history is also remove your data, so only use Localstorage as a cache/mirror of the data in the server.