There is a way using foobar2000 iOS.
You can connect to BubbleUPnP Server this way in iOS foobar2000:
Go into 'Media Servers' and add a 'User specified server' with this URL:
http://<user>:<password>@<public ip>:58050/DeviceDescription.xml
where:
- <user> and <password> are the user/password that you have set in the BubbleUPnP Server 'Network and Security' page
- <public ip> is the public ip address displayed in the status page
If it connects OK, you should see a browse tree whose root nodes are the UPnP media servers for which 'Make this Media Server available in BubbleUPnP for Android and foobar2000 for Internet access'
is enabled (in the 'Media Servers' page).