Best way to refresh/reload UIScrollView

Question

I have a method that adds some subviews (images/buttons) to my ScrollView.

The thing is that from outside of the ScrollView the user can tap a button that will change the content of the ScrollView.

Is there any decent way to "reset" the ScrollView better than:

for (UIView * view in myScrollView.subViews) {
    [view removeFromSuperview];
}

Note that this solution removes the bar to indicate the position on the ScrollView

Answer 1

Calling setNeedsDisplay is just going to redraw your scroll view, not actually remove the content inside of it.

As you've discovered, calling removeFromSuperview on all scroll view subviews will result in your scroll bars sometimes being removed as well (not great).

There are a couple of approaches around this: the first is to maintain a distinct array containing all the views you yourself have added to the scroll view. You can then just iterate through this array instead. In my view this is probably the best approach.

The other, slightly hacky, way is to test the views as you iterate through them:

for (UIView *view in self.contentView.subviews)
{
    if (![view isKindOfClass:[UIImageView class]])
        [view removeFromSuperview];
}

Because the scroll bars are themselves a UIImageView subclass this will not remove them. But then again, if you're using image views yourself they won't get removed either, and there's no guarantee in future iOS versions they will remain image views.

So much better to go with my first approach and just keep an array around with all the views you've added.

Answer 2

This is kind of an old thread, but a slightly easier method might just be to add a tag to the view's your adding to the UIScrollView, let's say 15. Then

for (UIView * view in _scrollView.subviews) {
    if (view.tag == 15) {
        [view removeFromSuperview];
    }
}

this way you can be sure that only the view's you have added get removed. Just a thought.