Since it "just" mirrors your phone it shouldn't access your OSX address book.
But since most people use iCloud to sync that address book with their Mac and their phone its moot. If you open WhatsApp on your phone, it will take a trip through your contacts and upload everything to their servers. Which, I still maintain, is stupid and unnecessary and the numer one reason why I never bothered with WhatsApp.
It's an IM client. So let me put my numer in and that's it. If I want to use it, I probably already know the people that also use it. So if they in turn also hae uploaded their number, I could search for it and add it. Have them confirm out connection and chat away. There is no need to grab all my contacts' information without their consent.
But since most people use iCloud to sync that address book with their Mac and their phone its moot. If you open WhatsApp on your phone, it will take a trip through your contacts and upload everything to their servers. Which, I still maintain, is stupid and unnecessary and the numer one reason why I never bothered with WhatsApp.
It's an IM client. So let me put my numer in and that's it. If I want to use it, I probably already know the people that also use it. So if they in turn also hae uploaded their number, I could search for it and add it. Have them confirm out connection and chat away. There is no need to grab all my contacts' information without their consent.