sample app.js showing background fetch.

app.js

// this sets the background color of the master UIView (when there are no windows/tab groups on it)
Titanium.UI.setBackgroundColor('#000');

// create tab group
var tabGroup = Titanium.UI.createTabGroup();

var win1 = Titanium.UI.createWindow({  
    title:'Tab 1',
    backgroundColor:'#fff'
});
var tab1 = Titanium.UI.createTab({  
    icon:'KS_nav_views.png',
    title:'Tab 1', window:win1
});

var label1 = Titanium.UI.createLabel({
  color:'#999',
	text:'I am Window 1',
	font:{fontSize:20,fontFamily:'Helvetica Neue'},
	textAlign:'center',
	width:'auto'
});

win1.add(label1);

tabGroup.addTab(tab1);  

// open tab group
tabGroup.open();

var wasFired = false;

Ti.App.iOS.setMinimumBackgroundFetchInterval(900);

Ti.App.iOS.addEventListener('fetch',function(e){
	Ti.API.info("FETCH - fired in background");
	wasFired = true;
});

Ti.App.addEventListener('paused', function(e){
	Ti.API.info("at this point Ti needs a background service to keep Kroll Happy");
	var service = Ti.App.iOS.registerBackgroundService({url:'bg.js'});
});

Ti.App.addEventListener('resumed', function(e){
	if(wasFired){
		alert("Success - fetch fired");
	}else{
		alert("Failure");
	}
});