Looking at iOS 11 logs using Console.app in High Sierra, I see that many important bits of information are masked like this:
nsurlsessiond Triggering periodic update to powerlog for client <private> dasd Trigger: <private> is now [<private>] Yelp Reservations Map Extension [19 <private> <private>] start
which makes it hard to see what's really happening. This happens on macOS too, and it can be changed with this command
sudo log config --mode 'private_data:on', as described here. How can I enable logging private data on iOS?