I was just about to link an app to a domain using universal links (or also refered to as associated domains; available since iOS 9). So far everything worked out and while testing with Safari I was able to open my app correctly, also parse path and query parameters of any URL.
But when I opened an URL that worked before with Safari from inside iMessage or Mail it failed. I found out that when opening an app that way each query parameter gets reformatted to lowercase characters, which is invalid towards my data handling. For example
https://www.example.com/path?paramNameOne=ValueOne¶mNameTwo=ValueTwo
is altered to
https://www.example.com/path?paramnameone=valueone¶mnametwo=valuetwo
So question is if there is a detail with this technology that I'm not aware of or - in case of a known bug - a propper strategy to cope with this issue.