Well she certainly had one in 2013:
http://abcnews.go.com/blogs/politics/2013/06/hillary-clinton-snaps-a-selfie-with-daughter-chelsea/
Unfortunately, I don’t find that story conclusive.
In the “selfie” with Meryl Streep, it was Streep holding the iPhone.
I’ve been searching for any comments made by her saying that she loves her iphone or gets an iphone.
Can’t find anything.
Yet.