The primary way of deploying App-Icon,
launch images, and tons of other icons at iOS
(and perhaps Mac OS X, QBS-389)
with Xcode 6 is by creating and building assets.

Keeping QCreator as the central development
point requires backup of the assets to a
Qt project and/or providing a way
to generate assets for XCode from Qt-project.

Support of Qt-application developers at least
by instructions and the best practices at this
page would be very much appreciated:

http://qt-project.org/doc/qt-5/platform-notes-ios.html