Instance Method

Adds an arc of a circle to the current path, specified with a radius and angles.

Parameters

center

The center of the arc, in user space coordinates.

The radius of the arc, in user space coordinates.

startAngle

The angle to the starting point of the arc, measured in radians from the positive x-axis.

endAngle

The angle to the end point of the arc, measured in radians from the positive x-axis.

clockwise

true to make a clockwise arc; false to make a counterclockwise arc.

Discussion

This method calculates starting and ending points using the radius and angles you specify, uses a sequence of cubic Bézier curves to approximate a segment of a circle between those points, and then appends those curves to the current path.

The clockwise parameter determines the direction in which the arc is created; the actual direction of the final path is dependent on the current transformation matrix of the graphics context. In a flipped coordinate system (the default for UIView drawing methods in iOS), specifying a clockwise arc results in a counterclockwise arc after the transformation is applied.

If the current path already contains a subpath, this method adds a line connecting the current point to the starting point of the arc. If the current path is empty, his method creates a new subpath whose starting point is the starting point of the arc. The ending point of the arc becomes the new current point of the path.

Constructing a Current Graphics Path

func beginPath()

Creates a new empty path in a graphics context.

func move(to: CGPoint)

Begins a new subpath at the specified point.

Appends a straight line segment from the current point to the specified point.

Adds a sequence of connected straight-line segments to the current path.

Adds a rectangular path to the current path.

Adds a set of rectangular paths to the current path.

Adds an ellipse that fits inside the specified rectangle.

func addArc(tangent1End: CGPoint, tangent2End: CGPoint, radius: CGFloat)

Adds an arc of a circle to the current path, specified with a radius and two tangent lines.

func addCurve(to: CGPoint, control1: CGPoint, control2: CGPoint)

Adds a cubic Bézier curve to the current path, with the specified end point and control points.

Adds a quadratic Bézier curve to the current path, with the specified end point and control point.

Adds a previously created path object to the current path in a graphics context.

func closePath()

Closes and terminates the current path’s subpath.

var path: CGPath?

Returns a path object built from the current path information in a graphics context.

func replacePathWithStrokedPath()

Replaces the path in the graphics context with the stroked version of the path.