The way I'd do it... Add a gesture recognizer to each of the image view you instantiate. The handler of that gesture needs to call a delegate method in the super view or controller where the image views are added to.
When calling that delegate in your controller or view just call
[self.view bringSubviewToFront:myTappedView];
*I'd recycle the image views... creating one for each tap is not a very good way to do it.
let me know if you need some more details.