You can't pass any additional parameters to motion finish
handler, so you need to implement some additional logic to bind tweened object with future text.
I would recommend to use TweenLite, with onComplete
and onCompleteParams
properties.
function switchText(evt:TextField, alpha:Number, newText:String, time:Number = 5):void {
TweenLite.to(evt, time, {alpha: alpha, onComplete: updateText, onCompleteParams: [evt, newText]});
}
function updateText(textField: TextField, value:String):void {
textField.text = value;
}