I have a question about rounding edges (For cube). For Example, I have a simple cube.
But, how do I round the edges like on the iPhone (For example):

[![Smoothed edge][1]][1]


I tried to do something like this, but this is the result: (picture #2)

How do I round the ends of my cube like this?: (picture #3)  
[![enter image description here][2]][2]


  [1]: https://i.sstatic.net/PJnyG.png
  [2]: https://i.sstatic.net/vvMHN.png