Converting groups to switchgroup animations
Switchgroups apply to groups of objects. Use switchgroups with grouped objects to control the visibility of the component (or child) objects within the group over time. At any given time during the animation of a switchgroup, either 0 or 1 child object of the switchgroup will be visible. You cannot make all child objects of a switchgroup visible at once.
In the SwitchGroup Properties dialog box, you can specify which object is displayed at which frame of the animation. The Child Animation list in the SwitchGroup dialog box displays each of the child objects and indicates at which frame each is displayed. To control how the objects of a switchgroup are displayed, you can edit the list to add objects by name (or a value of None to indicate no object) and specify at which frame that object becomes visible. An object stays visible until the animation reaches a frame in which another object becomes visible, or until it reaches a frame in which a value of None has been applied. Objects can be added more than once to the Child Animation list.
The effect of a switchgroup animation is very similar to a flip book of objects, in which each page contains a single image. As the pages are flipped, each image is shown in succession to create an animated effect.