Explicit opposite of UIViewAnimationOptionOverrideInheritedDuration?

just writing some iOS code. Getting rid of those dusty old non-block-based animations, and I've come across a bit of an annoyance. Hopefully it's just me running into my second left foot again.

Here's the scoop:

The default behavior for an animation block enclosed within another animation block is for the inner block to inherit the outer block's duration. I haven't pushed that assumption around too hard, but I'm willing to accept the apple docs at their word on that one. BUT, those same docs also say that we shouldn't depend upon that inheritance always working the same way in the future, and that furthermore, in the future, we might have to explicitly pass a flag to ensure that it does so.

So, my thought was, "surely there's a flag I can pass right now that will provide some future proofing." But I'll but durned if I've been able to find it.

Have any of you heard of something that's explicitly the opposite of UIViewAnima开发者_如何学运维tionOptionOverrideInheritedDuration?

...a UIViewAnimationOptionInheritDuration, perhaps?

If you find one, lmk! It'll set my nerves at ease to have that in there.

Given that there's no flag for that behavior right now, it's very likely that if this change is ever made, it will only apply to applications compiled after the change is introduced. In other words, existing apps will behave as they do right now, and you'll only have to change your code if you need to rebuild your application.