Transfer the Whatsapp Windows Phone Backup file to Iphone
Reading your WhatsApp chat history:

Go to http://inloop.github.io/sqlite-viewer/ and upload your message file. Select ZWAMESSAGE and press execute.



Restoring WhatsApp's chat history to iPhone

This method worked for me when migrating from WA for Android to WA for iPhone. This may not work with your WP backup of WA. If this should be the case, please leave a comment below.

Warning: Please create a separate backup of your iPhone before following the steps below.

Step by step instruction:


Make sure you have installed and configured WhatsApp on your iPhone.
Send someone a message. This will create the chat history file.
Connect your iPhone to a computer running iTunes.
Create a local, unencrypted backup of your iPhone.
Go to iTunes' settings and navigate to the tab "Devices"
Under "Device backups:" you should see your created backup. Right click on the backup entry and choose "Show in Finder" (or similar if you are running Windows).
Open the folder and navigate to "1b" (folder).
Find the file "1b6b187a1b60b9ae8b720c79e2c67f472bab09c0" and delete it.
Copy your Windows Phone's WhatsApp chat history file to the "1b" folder and rename it to "1b6b187a1b60b9ae8b720c79e2c67f472bab09c0".
In iTunes, navigate to your iPhone and select Restore. Select the just created backup and follow the instructions.


This process will import your old chat history into WA on the iPhone. You may need to re-register your phone number with WA.

Please let me know if it worked for you.