CGFloat

CGFloat is a floating-point scalar type used in Apple graphics and UI frameworks to represent coordinates, sizes, and other geometric values. It underpins common geometric types such as CGPoint, CGSize, CGRect, and transforms like CGAffineTransform, providing a single numeric type for drawing and layout operations across the APIs.

The exact underlying type of CGFloat depends on the platform’s word size: on 32-bit environments it is a 32-bit float, and on 64-bit environments it is a 64-bit double. In Objective-C, CGFloat is traditionally a typedef of float or double depending on architecture; in Swift, it is a platform-dependent type alias to Float on 32-bit and to Double on 64-bit platforms.

Because frameworks expect and return CGFloat values, code usually avoids mixing other floating-point types unnecessarily to preserve precision and minimize conversions. When working with graphics and layout, you typically use CGPoint, CGSize, and CGRect values composed of CGFloat components. On devices with different screen scales, a point corresponds to a varying number of pixels, so CGFloat coordinates often represent logical units rather than raw pixels.

API and constants: Core Graphics provides platform-appropriate constants such as CGFLOAT_MIN and CGFLOAT_MAX, which reflect the range of CGFloat on the running platform. In Swift, CGFloat integrates with the language’s FloatingPoint protocol, supporting standard numeric operations and interoperability with Double and Float as needed.

Summary: CGFloat offers a portable, architecture-aware floating type for core graphics and UI coordinates, enabling consistent APIs across 32-bit and 64-bit Apple platforms.