Mobiledic phone transfer program is a great desktop software that you can de-code it.

http://www.mobiledic.com/android-topic/transfer-contacts-from-iphone-to-android-phone.html

Woo, this is a big project which required a team to do it, I used a tool named Mobiledic phone transfer application to transfer my messages from Android to iphone, i think it's a nice program, you can crack or de-code it for learning.