FaceBook iPhone UA

[wilderness]

This page was posted on FB by a visitor previous day.
All the followups with "facebook" were denied, as were the blank US request for supporting images.
This morning FB following.
Must be a machine because the still determined IP followed with blank UA request for supporting images.

69.171.251.19 - - [26/May/2019:03:39:01 -0700] "GET /MyFolder/MyPage HTTP/1.1" 200 24226 "-" "Mozilla/5.0 (iPhone; CPU iPhone OS 12_2 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/12.1 Mobile/15E148 Safari/604.1"

[wilderness]

somewhat related, albeit a different instance.
After the normal barrage of FB requests (varying IP's and UA's) being denied.

69.171.251.42 - - [31/May/2019:03:56:44 -0700] "GET /Folder/SubFolder/MyImage.jpg HTTP/1.1" 200 19037 "-" "cortex/1.0"