I have a spinner that acts like a filter for searching among several categories. But the problem is that the spinner allows only one category to select from. Is there a way to obtain a multiple selection behavior for the spinner, or what other alternatives exists?
S spinner is designed to show one item at a time. You might get away by making a spinner of checkboxes, but it will be probably an awful user experience.
I would suggest you a ListView instead and CHOICE_MODE_MULTIPLE. You can add a listview to a dialog as shown in this answer: is it possible to create listview inside dialog?