I am planning to use a couple of picker controls and segmented controls (as a kind of control panel) embedded in a container view controller to control the contents of a second child view controller. However, according to Apple iOS Human Interface Guidelines, on an iPad a picker may not be presented in the main screen and must be presented in a popover:
On iPad, present a picker only within a popover. A picker is not suitable for the main screen.
How strict is this rule?
Would it be ok in my case to have the picker on the main screen in order to provide the required interactivity?
Clearly the answer to your question really depends on Apple, not on anything we developers might think or say. Your screen design looks very reasonable to me, but the issue is really whether Apple will approve it.
It might be better to ask if anyone has had an app approved with pickers outside of popovers.
Alternatively, you could ask if anyone has had an app rejected for using Pickers outside popovers.
Apple rules and common sense have a high degree of overlap, but where they differ the only thing that matters is Apple. Either ask them, or just submit your app for approval and see.
Good luck!