iOS9 does not load insecure resources from a secure page (SSL/HTTPS)

Question

I am trying to load a page into UIWebView on iOS9 using https:// URL. The page loaded includes CSS and images from an insecure server.

E.g. the page loaded:

Answer 1

On Xcode 8.3.3 (8E3004b)

It has changed to

App Transport Security Settings > Allow Arbitrary Loads in Web Content > YES