CALayer, anchorPoint and layer hierarchy

Question

Hi,

I try to use the anchorPoint in a layer hierarchy to move a layer with its sublayers. Unfortunately the sublayer did not move together with the root layer. In a custom NSView is set up my layer hierarchy like in the following snippet.

CALayer * rootLayer;
rootLayer = [[CALayer layer] retain];
rootLayer.position = CGPointMake(...);
[self.layer addSublayer:rootLayer];

subLayer = [[MapLayer layer] retain];
subLayer.position = CGPointMake(...);
[rootLayer addSublayer:baseLayer];

While handling a mouse event I want to set the anchorPoint of the rootLayer to move the whole layer hierarchy:

rootLayer.anchorPoint = CGPoint(0.7, 0.7);

I expect from this call, that the rootLayer moves together with its subLayer so that the anchor point is at the center of the view. What happens is, that the sublayer did not move. Only when I call:

rootLayer.anchorPoint = CGPoint(0.7, 0.7);
subLayer.anchorPoint = CGPoint(0.7, 0.7);

the layers behave as expected.

I thought setting the anchor point of the root layer would be enough. This is used in my Map application for OS X. There I set up the view and use the anchorPoint to move the whole map. With only one sublayer in the custom NSView the application behaves as expected.

Thanks in advance.

UPDATE: After a discussion with a colleague I set the bounds of the rootLayer and now it works.

CALayer * rootLayer;
rootLayer = [[CALayer layer] retain];
rootLayer.bounds = CGRectMake(0, 0, 256, 256);
rootLayer.position = CGPointMake(...);
[self.layer addSublayer:rootLayer];

// ...