如何覆盖WP8中另一个页面中的方法？

I am working on an app involving reading an NFC tag via the ProximityDevice class. The idea is when the tag is successfully read on the main_page, it will navigate to the second_page where all the processing of the tag content will be done. When it reaches the second_page, the app must not be able to read any tag anymore, unless it goes back to the main_page.I am working on an app involving reading an NFC