Swiping between Settings app and myApp not synchronising defaults?

Question

My app's behaviour is updating fine after changes to its prefs in the Settings app, just as long as Settings enters the background first - presumably triggering synchronisation of the changes to the prefs.

But using multitasking gestures to return (by swiping) directly to myApp after changes in Settings means that applicationDidBecomeActive or applicationWillEnterForeground read the defaults before Settings updates them.

So, where to put code to read defaults where it will pick up changes after Settings has synchronised?