Crosshatch in IOS using CoreGraphics?

Question

How would one crosshatch (apply a set of parallel lines at 45 degrees) across the fill of a shape in IOS using core graphics? Sample code?

(I'm specially interested in use with an MKPolygon in MKMapKit, however for the moment just trying to see if it's possible in a UIView using drawRect?. So fill the background of a UIView with crosshatch'ing)

Answer 1

Here's what I was talking about over in the Apple Developer Forum:

#import "CrossHatchView.h"

@implementation CrossHatchView

static  CGFloat  sides = 5.0;

- (void)drawRect:(CGRect)rect
{
    CGRect  bounds = self.bounds;

    UIBezierPath  *path = [UIBezierPath bezierPath];

    CGFloat  xCentre = CGRectGetMidX(bounds);
    CGFloat  yCentre = CGRectGetMidY(bounds);
    CGFloat  radius = 0.0;

    if (CGRectGetWidth(bounds) > CGRectGetHeight(bounds)) {
        radius = CGRectGetHeight(bounds) / 2.0;
    } else {
        radius = CGRectGetWidth(bounds) / 2.0;
    }
    CGFloat  angleIncrement = 2.0 * M_PI / sides;

    CGFloat  initialAngle = ( M_PI + (2.0 * M_PI / sides) ) / 2.0;

    for (NSUInteger  i = 0;  i < sides;  i++) {
        CGFloat  angle = initialAngle + i * angleIncrement;
        CGFloat  x = xCentre + radius * cos(angle);
        CGFloat  y = yCentre + radius * sin(angle);
        CGPoint  point = CGPointMake(x, y);
        if (i == 0) {
            [path moveToPoint:point];
        } else {
            [path addLineToPoint:point];
        }
    }
    [path closePath];
    [[UIColor cyanColor] set];
    [path addClip];

    CGRect  pathBounds = [path bounds];

    [path removeAllPoints];
    CGPoint  p1 = pathBounds.origin;
    CGPoint  p2 = CGPointMake(CGRectGetMaxX(pathBounds), CGRectGetMaxY(pathBounds));
    [path moveToPoint:p1];
    [path addLineToPoint:p2];
    path.lineWidth = 400.0;
    CGFloat  dashes[] = { 2.0, 2.0 };
    [path setLineDash:dashes count:2 phase:0.0];
    [[UIColor blackColor] set];
    [path stroke];
}

@end