customIndicator.js

// ==============================================================================
// Create custom loading indicator
// ==============================================================================
var indWin = null;
var actWin = null;
var indicatorShowing = false;
var actInd;
var actIndAndroid;

var screenWidth = Titanium.Platform.displayCaps.platformWidth;
var screenHeight = Titanium.Platform.displayCaps.platformHeight;

function showIndicator(title, color) {
	indicatorShowing = true;

	// add iphone elements
	if (Titanium.Platform.name == 'iPhone OS') {

		// window container

		indWin = Titanium.UI.createWindow({		
			height :screenHeight,
			width : screenWidth,
			zIndex : 0
		});

		// black view
		var indView = Titanium.UI.createView({
			height : 50,
			width : 125,
			borderRadius : 10,
			backgroundColor : color,
			opacity : 0.7
		});
		indWin.add(indView);

		// loading indicator
		actInd = Titanium.UI.createActivityIndicator({
			style : Titanium.UI.iPhone.ActivityIndicatorStyle.PLAIN,
			font : {
				fontFamily : 'Helvetica Neue',
				fontSize : 15,
				fontWeight : 'bold'
			},
			color : 'white',
			message : title,
			width : 210
		});

		actInd.show();
		indWin.add(actInd);
		indWin.open();

	} else {

		actIndAndroid = Titanium.UI.createActivityIndicator({
			bottom : 10,
			height : 50,
			width : 10,
			style : Titanium.UI.iPhone.ActivityIndicatorStyle.PLAIN
		});

		actIndAndroid.show();
		actIndAndroid.message = 'Loading...';
	}

}

function hideIndicator() {

	if (Titanium.Platform.name == 'iPhone OS') {

		if (indicatorShowing == true) {
			if (actInd) {
				actInd.hide();
			}
			if (indWin != null) {
				//Ti.UI.currentWindow.remove(indWin);
				indWin.close();
				indWin = null
			}
			indicatorShowing = false;
		}

	} else {
		if (actIndAndroid) {
			actIndAndroid.hide();
			indicatorShowing = false;
		}
	}
}

var indicator = {

}
exports.registerListener = function() {
	// ==============================================================================
	// Add global event handlers to hide/show custom indicator
	// ==============================================================================
	Titanium.App.addEventListener('show_indicator', function(e) {
		if (e.title == null) {
			e.title = 'Loading... ';
		}
		if (e.color == null) {
			e.color = "#000";
		}
		if (indicatorShowing == true) {
			// return;
			hideIndicator();
		}
		showIndicator(e.title, e.color);
	});

	Titanium.App.addEventListener('hide_indicator', function(e) {
		hideIndicator();
	});
}

exports.indicator = indicator;
===================================================
app.js

var indicator = require('indicator');
indicator.registerListener();
=============================

to show indicator just call Ti.App.fireEvent("show_indicator"); from any window.
to hide call Ti.App.fireEvent("hide_indicator");