Get the 'Z value' of a point

Question

I'm implementing an app' in which i use some 'CALayers' to create some forms. For example :

testLayer = [CALayer layer];
testLayer.frame = layerRect;
testLayer.position = self.view.center;

CGFloat degrees = 90.0;
CGFloat radians = DegreesToRadians(degrees);
CATransform3D rotation = CATransform3DMakeRotation(radians, 0.0, 1.0, 0.0);
CATransform3D translation = CATransform3DMakeTranslation(Layer_Size/2, 0.0, Layer_Size/-2);
CATransform3D position = CATransform3DConcat(rotation, translation);
testLayer.transform = position;

This layer is add in a :

transformLayer = [CATransformLayer layer];
[transformLayer addSublayer:testLayer];
transformLayer.anchorPointZ = Layer_Size/-2;

But i want to get the Z value of a point which is on the testLayer and is named testLayerPoint (of type 'UIView', with size 1x1), because when i want to project the coordinates into the plan of the principal view like this :

CGRect rectTest = [testLayerPoint.layer convertRect:[[testLayerPoint.layer presentationLayer] frame] toLayer:self.view.layer];

The code :

NSLog(@"%f", rectTest.x);

gives not the correct coordinates… So i want to get the Z value directly.

Thanks !

Answer 1

If by Z value you're referring to the zPosition, that can be found by calling the zPosition property on any CALayer . It defaults to 0.

From the docs:

Changing the value of this property changes the the front-to-back ordering of layers onscreen. This can affect the visibility of layers whose frame rectangles overlap.

The value of this property is measured in points.