How are the properties Layer related to its Frame and Bounds, and how do they affect the element's display?

In iOS, each CALayer has three key properties related to its size and position: frame, bounds, and position.

• bounds — a rectangle (CGRect) defining the internal size of the layer in its own coordinate system. Typically, the origin of bounds is (0,0), and the size is the width and height of the layer.

• frame — a rectangle describing the position and size of the layer in the coordinate system of its superlayer. The frame is calculated based on bounds, position, and transform.

• position — a point in the superlayer's coordinate system that corresponds to the layer's anchor point.

Relationship:

• Changing bounds alters the internal size of the layer without affecting its position.
• Changing frame modifies the position and size of the layer in the superlayer, and bounds and position may be recalculated.
• position and anchorPoint determine where exactly in the superlayer the layer is located.

Impact on display:

• Changing bounds will change the size of the layer's content.
• Changing frame will change the position and size of the layer on the screen.
• Incorrect understanding of the relationship can lead to unexpected display issues, such as displacement or distortion of the layer.

Example:

let layer = CALayer()
layer.bounds = CGRect(x: 0, y: 0, width: 100, height: 100) // size of the layer
layer.position = CGPoint(x: 50, y: 50) // position in superlayer
// frame will be CGRect(x: 0, y: 0, width: 100, height: 100) considering anchorPoint (default 0.5,0.5)

Thus, frame is a derived property depending on bounds, position, and anchorPoint, and it determines how the layer is displayed in the hierarchy.