What is the best way to teach seniors how to use iphone?

My Great Uncle recently got an iphone 6, and only understands how to make phone calls and send texts. I'd like to know an effective way to teach him everything he needs to know, without it taking forever.

They have books especially for seniors. You, someone in your family, or a family friend could then teach him. He could even pay them to teach him.

He didn't get so old depending on machines to think for him. That's where common sense went that people used to have. Just have a plain conversation with him instead of trying to tether him to an addiction. Oh, you think you aren't addicted? Do without your phone for 3 days and see what you feel like.

Don't put a time limit on it.