CGContextSetLineDash

CGContextSetLineDash is a function in the Core Graphics framework of Apple's iOS and macOS SDKs, used to customize the appearance of lines drawn in a graphics context. It allows developers to apply a dashed or patterned line style to paths, shapes, or strokes by defining a sequence of on and off segments. The function is particularly useful for creating visual effects such as grid lines, borders, or decorative outlines.

The function takes three parameters: the graphics context, the phase offset, and an array of dash lengths. The phase offset determines where the dash pattern begins relative to the starting point of the line. The dash lengths array specifies alternating lengths of visible (on) and invisible (off) segments, measured in points. For example, an array like [5, 3] would produce a line with 5 points of visible stroke followed by 3 points of gap, repeating throughout the line.

CGContextSetLineDash is often used in conjunction with other line-related functions such as CGContextSetLineWidth to further refine the appearance of strokes. It is important to note that the function only affects lines drawn after it is called within the same graphics context. To reset the dash pattern to a solid line, developers can use CGContextSetLineDash with an empty array or call CGContextSetLineDash with a nil array and a phase of 0.

This function is part of the Core Graphics API, which is a low-level framework for rendering 2D graphics. It is commonly used in applications requiring custom drawing, such as vector-based illustrations, diagrams, or UI customization. Developers working with Core Graphics should ensure compatibility with the target platform, as some features may vary between iOS and macOS.