title: How to get Beats per minutes of a song in objective-c
body: <p>I did lots of R&amp;D but did not get any good answer. I am working on music type app in iphone and i have to categorized songs on the basis of beats per minute.So my first task to find out BPM of song.How can we do that? I got some answers like:
  1.using MPMediaItemPropertyBeatsPerMinute property of MPMediaItem class ,will it work fine. I have doubt on this because some guys said it will return null.
  Do you have any sample code or logic to get this. </p>
  
  <p>Thanks in advance.</p>