As far as iPad’s memory is concerned, it’s not infinite. Hence no infinite canvas can really exist.
You can however have the canvas automatically enlarge while you draw. Here is how:
- Make sure your canvas size in Preferences > Canvas Size is Auto.
- Draw or move objects towards the right or bottom edge and the canvas will automatically enlarge, no questions asked.
- If you’d like to have some more space to the left or to the top, select all shapes and move them to the right or to the bottom.