Available in iOS 3.0 and later.
CATransformLayer objects are used to create true 3D layer hierarchies, rather than the flattened hierarchy rendering model used by other
Unlike normal layers, transform layers do not flatten their sublayers into the plane at
Z=0. Due to this, they do not support many of the features of the
CALayer class compositing model:
Only the sublayers of a transform layer are rendered. The
CALayerproperties that are rendered by a layer are ignored, including:
contents, border style properties, stroke style properties, etc.
The properties that assume 2D image processing are also ignored, including:
masksToBounds, and shadow style properties.
opacityproperty is applied to each sublayer individually, the transform layer does not form a compositing group.
hitTest:method should never be called on a transform layer as they do not have a 2D coordinate space into which the point can be mapped.
Returns the farthest descendant of the receiver in the layer hierarchy (including itself) that contains a specified point.
A point in the coordinate system of the receiver's superlayer.
The layer that contains
nilif the point lies outside the receiver’s bounds rectangle.
Transform layers do not support hit-testing. As a result, you should not send
hitTest:messages to transform layers.