CGAffineTransform and scaling to center of the image

Question

I started studying objective-c using the iPhone and iPad apps for Absolute Beginners by Rory Lewis book but i got stuck on the 5th chapter.

I want to make a

Answer 1

Old question... but just in case others come looking:

The CGAffineTransform acts (rotates, scales) around an anchorPoint.

If you are sizing to 0, 0 then your anchor point is set to 0, 0. If you want it to size to a different point, such as the center of the image, you need to change the anchor point.

The anchor is part of a layer

So if you have a UIImageView called imageview, you would make a call like this to set the anchor to the center of imageview:

[imageview.layer setAnchorPoint:CGPointMake(0.5, 0.5)];