GuideView | 动态可定制引导页

Marker is not view and you can't get View from it. But anyway you can create dummy transparent View and place it over the selected marker programmatically, then pass it to ShowCaseView library via setTargetView method. So, you need root view around your MapFragment or MapView, e.g RelativeLayout (activity_main.xml):

This looks like a known issue. Please see http://issuetracker.google.com/150325706#comment25 for how to use a version of R8 where this has been fixed.

collectionView(_:cellForItemAt:) is a collection view delegate method which tends to get called more than once, and there are a lot of factors that trigger the call like:

1. The number of visible cells you've got, depending on the height of the collection

2. When scrolling through cells to reuse them

Or triggers to change/refresh the collection like:

1. reloadData(), reloadItems(at:) or reloadSections(_:)

2. Perhaps a layoutIfNeeded() call from the view that contains this collection view.

and more...

The point is, the function getting called more than once is pretty normal. Your answer probably lies in "What triggers the call?"

EDIT:

To update your pageControl according to the index of the collection: