Actually I did try the boolean on app launch (apparently developers think alike :)). It is still messy and unreliable. We do not have control over .onAppear and .onDisappear invocations by the framework in the context of an entire complexity of a view hierarcy. That is precisely why I hesitate to rely on them unless I really have to. I am also hoping that gaps between SwiftUI and UIKit with be narrowed down in the upcoming WWDC. Thanks again for taking time out to respond.

I did try out your suggestion and I don't think it works completely the way we imagined. At launch, The primary view's onAppear is invoked even when the primary view is in collapsed state ... so that kind of complicates things for initial scenarios. Just thought I give an update

Thanks @BabyJ for the response. Though I try to avoid using .onAppear and .onDisappear callbacks unless really I have to ... in this case this might do the trick. I will give it a spin. I was so fixated that this check wasn't provided explicit in the framework api... now I have to confess I am a bit embarrassed that I didn't think of this myself :) Thanks again for taking time. Appreciate your suggestion.

Settled on the design pattern of relegating the parameter to a subview.