Didn't work on fresh Titanium project before and was too fast spinning. Fixed for demonstration purposes.

app.js

var win = Ti.UI.createWindow({ backgroundColor: '#000' });
var v = Ti.UI.createView({ width: 50, height: 50, backgroundColor: '#fff'});
 
var s = require('spinner').Spinner(
  v, // View to spin
  30 // Degrees to spin per millisecond
); // Auto-starts
 
// Stop
s.stop();
 
// Start
s.start();
 
// Change speed
s.start(100);
win.add(v);
win.open();

spinner.js

function Spinner(view, _speed) {
    var speed = _speed || 5,
        timeout,
        spinning = false,
        degrees = 0;
      
    var self = this;     
            
    function rotate() {
        var t = Ti.UI.create2DMatrix();
        degrees = degrees + speed;
        t = t.rotate(degrees);
        
        var a = Titanium.UI.createAnimation();
        a.transform = t;
        a.duration = 1;
        
        view.animate(a);
        
        loop();
    }
    
    function loop() {
        
        if (spinning === true) {
            timeout = setTimeout(rotate, 1);
        }
    }
    
    this.stop = function () {
        
        if (spinning === true) {
            spinning = false;
            timeout && clearTimeout(timeout);
        }
        
        return this;
    }
    
    this.start = function (_speed) {
        
        if (spinning === false || (_speed && _speed != speed)) {
        
            if (_speed) {
                speed = _speed;
                this.stop();
            }
       
            spinning = true;
            loop();
        }
        
        return this;
    }
    
    return this.start();
}

exports.Spinner = Spinner;