Only supporting a single keyframe at a given time is an easy source of error

[sibljon]

Please correct me if I'm wrong, but it seems that only one IFTTTAnimationKeyFrame can be added to an animation for a given "time". I believe this to be an easy source of confusion. For example, the following doesn't change the view's alpha at all:

        [self.animation addKeyFrames:@[
            [IFTTTAnimationKeyFrame keyFrameWithTime:time0 andFrame:offscreenFrame],
            [IFTTTAnimationKeyFrame keyFrameWithTime:time0 andAlpha:0],
            [IFTTTAnimationKeyFrame keyFrameWithTime:time1 andFrame:view.frame],
            [IFTTTAnimationKeyFrame keyFrameWithTime:time1 andAlpha:1],
            [IFTTTAnimationKeyFrame keyFrameWithTime:time2 andAlpha:0],
            [IFTTTAnimationKeyFrame keyFrameWithTime:time2 andFrame:offscreenFrame],
        ]];

In fact, the above fails silently, only changing the view's frame. but the following does change the alpha:

        [self.animation addKeyFrames:@[
            [IFTTTAnimationKeyFrame keyFrameWithTime:time0 andFrame:offscreenFrame],
            [IFTTTAnimationKeyFrame keyFrameWithTime:time0 + 1 andAlpha:0],
            [IFTTTAnimationKeyFrame keyFrameWithTime:time1 - 1 andFrame:view.frame],
            [IFTTTAnimationKeyFrame keyFrameWithTime:time1 andAlpha:1],
            [IFTTTAnimationKeyFrame keyFrameWithTime:time2 - 1 andAlpha:0],
            [IFTTTAnimationKeyFrame keyFrameWithTime:time2 andFrame:offscreenFrame],
        ]];

[sibljon]

Heh, ok, so looks like I had a gap in my understanding. The clear solution is to create a IFTTTFrameAnimation and a IFTTTAngleAnimation instance (rather than trying to combine them as I did above).