objective-c - get x & y & z position for CALayer

Question

I want to get x,y,z position of CAlayer can i get it directly or i should use transform matrix ?

i know how to set its value

[layer setValue:value forKeyPath:@"transform.translation.z"];
[layer setValue:value forKeyPath:@"transform.translation.x"];
[layer setValue:value forKeyPath:@"transform.translation.y"];

but i don't know how to get them back ?

if i should use transform matrix what are the equations ?

and how can i get its rotation angle ?