Ok, the problem solved itself with update to Qt 5.11.2 (while running iOS12). Thanks for reading.

@patrik08 : I am trying to mix normal QT application with Swift code in order to load the receipt of purchasing an app from app store as requested in this, since you have good experience with Swift and QT C++ code, i would appreciate if you provide an example for this case to the tracker. Thanks alot

https://bugreports.qt.io/browse/QTBUG-76665