iOS - Drawing pencil stroke for iPhone app - ios

Question

I'm working on a Drawing application where I need to achieve pencil effect similar to Apple notes app.
So I subclasses the UIView and write the following code.
CGPoint midPoint(CGPoint p1, CGPoint p2)
{
return CGPointMake((p1.x + p2.x) * 0.5, (p1.y + p2.y) * 0.5);
}
#interface DrawingView () {
CGPoint currentPoint;
CGPoint previousPoint1;
CGPoint previousPoint2;
CGMutablePathRef path;
}
#end
#implementation DrawingView
- (id)init
{
self = [super init];
if (self != nil) {
path = CGPathCreateMutable();
}
return self;
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
previousPoint1 = [touch previousLocationInView:self];
currentPoint = [touch locationInView:self];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
previousPoint2 = previousPoint1;
previousPoint1 = [touch previousLocationInView:self];
currentPoint = [touch locationInView:self];
CGPoint mid1 = midPoint(previousPoint1, previousPoint2);
CGPoint mid2 = midPoint(currentPoint, previousPoint1);
CGMutablePathRef subpath = CGPathCreateMutable();
CGPathMoveToPoint(subpath, NULL, mid1.x, mid1.y);
CGPathAddQuadCurveToPoint(subpath, NULL, previousPoint1.x, previousPoint1.y, mid2.x, mid2.y);
CGRect bounds = CGPathGetBoundingBox(subpath);
CGPathAddPath(path, NULL, subpath);
CGPathRelease(subpath);
[self setNeedsDisplayInRect:bounds];
}
- (void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextAddPath(context, path);
CGContextSetLineCap(context, kCGLineCapRound);
CGContextSetLineWidth(context, 5.0f);
CGContextSetStrokeColorWithColor(context, [UIColor lightGrayColor].CGColor);
CGContextSetBlendMode(context, kCGBlendModeNormal);
CGContextSetAlpha(context, 1.0f);
CGContextStrokePath(context);
}
This works fine and it produces the output like the following.
But I need the output like the following picture. Similar to Apple Notes app.
Any ideas how to achieve this.

Answer 1

Download the pencil texture and set this image as your CGContext stroke color.
private var pencilTexture = UIColor(patternImage: UIImage(named: "pencil_texture")!)
ctx.setStrokeColor(pencilTexture.cgColor)