Custom URLs

[Dan Friedman]

I need a little help here...

I am creating a mobile app for a client that wants to simply launch another app.  To do this, I am trying to use a custom url to launch an external app.  For example:

launch url "fb:"

This works fine on Android, but on iOS, I get "no association" (yes, Facebook is installed).  Then I read that you have to enter the Custom URLs you want to use in the "App URL Query Whitelist" area in the Application Builder.   Is this true?   Why does the app have to know at compile time what URLs are going to be opened?  In my app's case, client can change and edit the list on a server, so the list of apps to launch are received by the our app at launch.

"mailto:", "http:", "music:" and "tel:" all work just fine on iOS without being included in the App URL Query Whitelist.

Anyone have any insight to this process?

Thanks in advance!
-Dan