title: Android NFC read Tag only on button click
body: <p>I am slowly learning Android. Currently I am on NFC, I have studied a couple of tutorials and I start understanding a bit better how it works and how to read and write tags, what I can do now on the ones I bought.
  Most people want their app to start as soon as they are close to a tag but for learning purposes I would like to start the discovery only when I hit a button, in other words, I want to control the discovery. 
  I understand that in order to have the app starting immediately, we implement the filter  ACTION_NDEF_DISCOVERED in the Manifest.xml
  I also read that filtering with intents works only if our app is not in foreground. If our app is running in the foreground, it won't be notified, so we have to use NFC Foreground dispatch.</p>
  
  <p>What I can't figure out is how I can manipulate the filter and the foreground in order they only react to my click of a button.</p>
  
  <p>My other question is : Is it going to work for both Read and Write buttons?</p>
  
  <p>Could somebody please help? If you give me some code, please be so kind to explain it, I am really after learning and understanding :-)</p>
  
  <p>Cheers.</p>