TurtleBezierPath is a UIBezierPath subclass for Turtle Graphics: a simple, intuitive drawing system developed my Seymour Papert for the Logo programming language.

The Turtle is a drawing cursor that follows the commands: home, turn, forward, leftArc, rightArc, up and down. As the Turtle moves, it draws a path in its wake. Many shapes are much easier to draw this way.

Demo app

The app requires iOS 7 and allows you to explore Turtle Graphics drawing with simple controls. It's fun too!

Installation

Simply add TurtleBezierPath.h and TurtleBezierPath.m to your project, or add it as a Cocoapod named TurtleBezierPath.

TurtleBezierPath will work with both ARC and MRC projects.

@interface

Both NSCoding and NSCopying are fully supported.

@property( nonatomic, assign ) CGFloat bearing; // The compass bearing of the Turtle in degrees

• 0 - North
• 90 - East
• 180 - South
• 270 - West

@property( nonatomic, assign ) BOOL penUp; // When YES the Turtle will move but not draw

-(CGRect)boundsWithStroke; // The bounds rect of the path including the stroke width

-(void)home; // Move the Turtle to ( 0, 0 ) and set the bearing to 0 degrees

-(void)forward:(CGFloat)distance; // Move the Turtle forward distance points

-(void)turn:(CGFloat)angle; // Add angle degrees to the Turtle's bearing

-(void)leftArc:(CGFloat)radius turn:(CGFloat)angle; // Move the Turtle angle degrees in an anti-clockwise arc of radius points

-(void)rightArc:(CGFloat)radius turn:(CGFloat)angle; // Move the Turtle angle degrees in a clockwise arc of radius points

-(void)down; // Move the pen down

-(void)up; // Move the pen up

-(void)centreInBounds:(CGRect)bounds; // Transform the path so that the home position is in the centre of the bounds

@end