Improving the efficiency of multiple concurrent Core Animation animations
- by Alex
I have a view in my app that is very similar to the month view in the built-in Calendar app. There's a subview that holds the individual cells (a custom UIView subclass that draws text into its layer), and when the user navigates to the next "month", I create the new cells and slide the view to show them. When the animation stops, I remove the old, hidden cells and set things up so it's ready to go for the next animation.
This all works nicely. However, I'd like to animate the cells' text color, as in the Calendar app, so that the outgoing ones transition to a lighter color and the incoming ones transition to a darker color. The problems is that I can have as many as 70 cells, so doing individual animations is very slow -- between 5-10 fps on my iPhone 3GS.
I'm trying to find a less computationally intense way of doing this. My reading of the Shark results is that the majority of the time is spent redrawing the text for each frame for each frame. This makes sense, since text rendering is hardly the cheapest operation.
I've considered creating a second view -- one holding the "outgoing" state and one holding the "incoming" state and using a single opacity animation to gradually reveal the updated cells while both are sliding. I'm concerned that instead of having 70 cells, I'll have 140, which seems like a lot of views. So, is that too many views or would there be a better way of doing this?
