Create a POPAnimationGroup

[cfcommando]

cc @kimon

(Or alternatively, call it POPCompositeAnimation, or something.)

This would probably depart from CoreAnimation APIs in that rather than implicitly creating dependencies with timing, it would be necessary to create dependencies, i.e:

• -[POPCompositeAnimation addAnimation:firstAnim];
• -[POPCompositeAnimation addAnimation:secondAnim afterAnimation:firstAnim];
• -[POPCompositeAnimation addAnimation:alsoSecondAnim afterAnimation:firstAnim];
• -[POPCompositeAnimation addAnimation:lastAnim afterAnimations:@[secondAnim, alsoSecondAnim]];

...or something to that effect. The limitation of the above API would be that they would all apply to a single object if abstracted as such, unless one added an additional parameter to determine which objects the animations should apply to.

An alternative approach might be to create sub-animators, which might end up with a cleaner / more elegant API than the above suggested API, depending on how that's structured.

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My use case for this is that I'm animating a view scaling to aspect fit inside another view so the rasterized scaling doesn't stretch, and I want to follow that animation up with a (possibly more expensive but much shorter) animation to extend the remaining dimension of the fitted rectangle into the full rectangle.

(Less abstractly, I'm writing a seamless transition from a cell in a collection view to a view controller by way of a zooming animation from the cell into the view controller, and their rects have different aspect ratios. I'm scaling the rectangle while preserving the aspect for as long as possible)

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[pronebird]

I use CAAnimationGroups a lot when I need to animate bunch of properties together. How do you do this in POP?

👍 on that feature request.

[kimon]

The best way to have a single Pop animation apply to a number different objects/properties is through the use of a custom property, on the containing class. You route the sub-application depending on your specific logic. Applying an animation to multiple objects is something we've considered, but as you point out, would require considerably different (and likely more complex) API.

[cfcommando]

@pronebird 's feature request is related but not what the issue describes; I think that a way of describing a sequence of animations would be fairly useful. i.e. transitioning a decay animation into a spring animation while preserving velocity, or seamlessly transitioning between linear/decay/spring animations as the situation calls for it, or using a cheap operation for most of an animation and using a slightly more expensive one for a shorter amount of time, for effect.

It's not currently impossible, but it is very awkward.

[pronebird]

@kimon @cfcommando sorry guys, didn't get it right. What you want certainly can be done using POPAnimationDelegate. It probably wouldn't be hard to make a shared delegate for couple of animations.

[ghost]

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