Creates a nPointed star with the odd point at the center-top.

NPointedStar.h

#import <SpriteKit/SpriteKit.h>

@interface NPointedStar : SKShapeNode

/** Creates a nPointed star with the odd point at the center-top.
 
 Must provide all parameters normally added to a SKShapeNode except for the path.
 
 Example:
 (Inside a SKScene class)
 NPointedStar* fivePointStar = [[NPointedStar alloc] initWithRadius:20.0f nPoints:5 fatness:1.0f];
 fivePointStar.position = CGPointMake(self.size.width/2, self.size.height/2);
 fivePointStar.fillColor = [SKColor yellowColor];
 [self addChild:fivePointStar];
 
 */
-(instancetype)initWithRadius:(float)radius nPoints:(NSUInteger)points fatness:(float)fatness;

@end

NPointedStar.m

#import "NPointedStar.h"

@implementation NPointedStar

-(instancetype)initWithRadius:(float)radius nPoints:(NSUInteger)points fatness:(float)fatness
{
    if (self = [super init]) {
        CGMutablePathRef starPath = CGPathCreateMutable();
        float alpha = 2 * M_PI / points/2;
        for (NSUInteger i = 0; i < points*2+1; i++) {
            float r = radius* (i%2+fatness)/2;
            float omega = i*alpha;
            if (i == 0) { // Change '-r' to 'r' if the odd-th number of point should point down
                CGPathMoveToPoint(starPath, NULL, -r*sinf(omega), -r*cosf(omega));
            } else {
                CGPathAddLineToPoint(starPath, NULL, -r*sinf(omega), -r*cosf(omega));
            }
        }
        self.path = starPath;
    }
    return self;
}

@end