Based on another message I remember reading you should be able to open
the phonegap.plist and look for ExternalHost and add *.mydomain.com.
Again, I’m not the iOS expert so someone else will probably have a
better solution.
Posted on08 October 2011.
[...] You must edit phone gap preferences and white list external pages. Read: Xcode phonegap White list rejection [...]

This is the best solution for external links for your apps.