A class to monitor background updates to a HTML based iPhone application

cache_manager.js

/*

A class to monitor background updates to a HTML based iPhone application.
Note that this needs to be used in conjunction with an HTML5 Cache Manifest file

This originated from some sample code in this book:
http://www.amazon.com/Building-iPhone-Apps-HTML-JavaScript/dp/0596805780

*/

MyCompany.app.CacheManager = function() {
  return {
    cacheStatusValues: {
      0: 'uncached', 1: 'idle', 2: 'checking', 3: 'downloading', 4: 'updateready', 5:'obsolete'
    },
    isUpdating: false,
    init: function() {
      // The 4 events we are concerned with are:
      //    'downloading' - fired at the beginning of a needed update
      //    'progress'    - fired during the download of a needed update
      //    'cached'      - fired at the end of the very first download
      //    'updateready' - fired at the end of all other successful updates,
      //    'noupdate'    - for some unknown reason, this needs to be checked as well
      window.applicationCache.addEventListener('downloading', this.onDownloading,       false);
      window.applicationCache.addEventListener('progress',    this.onDownloading,       false);
      window.applicationCache.addEventListener('updateready', this.onUpdateReady,       false);
      window.applicationCache.addEventListener('cached',      this.onUpdateReady,       false);
      
      window.applicationCache.addEventListener('noupdate',    this.onNoUpdate,          false);
 
      window.applicationCache.addEventListener('checking',    this.onCacheEvent,        false);
      window.applicationCache.addEventListener('error',       this.onCacheEvent,        false);
      window.applicationCache.addEventListener('obsolete',    this.onCacheEvent,        false);
      // window.applicationCache.update();
    },
    onNoUpdate: function(e) {
      if (window.applicationCache.status == window.applicationCache.UPDATEREADY) {
        MyCompany.app.CacheManager.isUpdating = true;
        MyCompany.app.CacheManager.reload();
      } else {
        MyCompany.app.CacheManager.onCacheEvent(e);
      }
    },
    onDownloading: function() {
      konsole.log('Downloading update...');
      if (MyCompany.app.ApplicationController.panel && !MyCompany.app.CacheManager.isUpdating) {
        MyCompany.app.ApplicationController.onDownloadingUpdate();
      }
      MyCompany.app.CacheManager.isUpdating = true;
    },
    onUpdateReady: function(e) {
      konsole.log('Update has been downloaded.');
      MyCompany.app.CacheManager.isUpdating = true;
      MyCompany.app.CacheManager.reload(); 
    },
    reload: function() {
      try { 
        window.applicationCache.swapCache(); 
        konsole.log('Swapped/updated the application cache.');
      } catch (err) { 
        konsole.error('could not swap cache'); 
      }
      window.location.reload();
    },
    onCacheEvent: function(e) {
      var online, status, type, message;
      online = (navigator.onLine) ? 'yes' : 'no';
      status = MyCompany.app.CacheManager.cacheStatusValues[window.applicationCache.status];
      type = e.type;
      message = 'Cache: online(' + online + ')' +
        ' event(' + type + ')' +
        ' status(' + status + ')';
      if (type == 'error' && navigator.onLine) {
         message+= ' There was an unknown error, check your Cache Manifest.';
      }
      console.log(message);  
    }
  }
}();