Frame vs Bounds; explained with co-ordinate System

Introduction

frame and bounds are among the most fundamental properties of UIView. Although they often appear similar, they represent different coordinate systems and behave differently when modified.

Understanding these properties is essential for building custom views, animations, scrollable content and complex user interfaces.

What is Frame?

The frame defines the position and size of a view in the coordinate system of its superview.

What is Bounds?

The bounds defines the view's own internal coordinate system. It describes the drawable area of the view and controls how its content is positioned inside the view.

Frame vs Bounds

Although both properties describe the geometry of a view, they are measured in different coordinate systems.

Changing the frame usually affects the view's position or size relative to its parent, whereas changing the bounds affects how content is displayed inside the view.

Example

let view = UIView(
    frame: CGRect(
        x: 20,
        y: 40,
        width: 200,
        height: 120
    )
)

print(view.frame)
print(view.bounds)

Comparison