Summary
An activity indicator is used to inform the user that an operation is proceeding. It can be placed but not sized in iOS and the only method on it is to toggle animation on or off using setAnimated(). See ProgressIndicator setAnimated()..
Example
root = new View("ipad-portrait");
var animated = false;
b = root.createButton(400,200);
b.setText("Animate");
ai = root.createActivityIndicator(500,500, 50,50);
ai.setAnimated(animated);
function click(sender) {
animated = !animated;
ai.setAnimated(animated);
}
b.onClick(click);
document.wait();