Is it possible to add a CALayer inside a UIView?

In iOS, UIView already contains a basic CALayer, which can be accessed through the layer property. Additional CALayers can be added inside a UIView by adding them as sublayers to this layer.

Example of adding a CALayer inside a UIView:

let view = UIView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))

let sublayer = CALayer()
sublayer.frame = CGRect(x: 10, y: 10, width: 80, height: 80)
sublayer.backgroundColor = UIColor.red.cgColor

view.layer.addSublayer(sublayer)

Thus, a CALayer cannot be added directly to a UIView as a separate element, but it can be added as a sublayer to view.layer. This is the standard way to extend the visual content of a UIView.