on page 47 of the pdf, section 4.2 discusses grouping animations in @NSAnimationContext@.
[NSAnimationContext beginGrouping]; [[NSAnimationContext currentContext] setDuration:2.0f]; // your code here [NSAnimationContext endGrouping]; ...*_Any_* animation between the beginGrouping and endGrouping calls will animate for the duration speciﬁed.
i went back to section 3.1 Keyframe Animations and opened up the example and tried it out, and i found that since we explicitly set the duration for this animation to be 2.0f (page 28 of the pdf, @originAnimation@ method) that grouping in @NSAnimationContext@ with a different duration specified had no effect. only after i commented out the line where the duration is set did the group context duration have any effect.
i know it’s nit picky but i just happened to try this out on that example and had this happen, or not happen i guess.
of course i see now that this is all explained 2 paragraphs later…