Uploading friends to your social media

Hi I was wondering if you are supposed to ask your friends persmission to mention them and/or upload photos of them from when you've hung out together to your blog or other social media. The few times I have i've asked. It feels a little silly. Do other people ask first and are you supposed to? The few times someone i've hung out with has uploaded a photo of me they haven't asked first. It felt super weird but also flattering and I said nothing about it. I guess there must be some unwritten social rule about this too so what is it? I'm also thinking if you hang out with a friend all day, write about the day in your blog and dont even mention them maybe it's offensive like you want to hide them.