Basic Loading Indicator that I used in Titanium Classic Apps

app.js

var loading = require('loading');

loading.start();

setTimeout( function(){ loading.stop(); }, 2000 );

loading.js

module.exports = (function(){
    
    var loadWin = Ti.UI.createWindow({
        backgroundColor: 'black',
        opacity: 0.7,
        height: '20%',
        width: '60%',
        borderRadius:10
    });
    
    var actInd = Titanium.UI.createActivityIndicator({
        message:"Loading...",
        height:50,
        width:'auto',
        color:'#fff'
    });
    
    if (Ti.Platform.name === 'iPhone OS'){
        actInd.style = Ti.UI.iPhone.ActivityIndicatorStyle.PLAIN;
    }else{
        actInd.style = Ti.UI.ActivityIndicatorStyle.PLAIN;
    }
    
    loadWin.add(actInd);
    
    var start = function(_message){
        actInd.message = ('string' == typeof _message) ? _message : "Loading...";
        actInd.show();
        loadWin.open();
    };
    
    var stop = function(){
        loadWin.close();
        actInd.hide();
    };
    
    return {
        start: start,
        stop: stop
    };
})();

For Alloy projects nl.fokkezb.loading is my first choice

https://github.com/FokkeZB/nl.fokkezb.loading