Masking a chip out of a UIView.

gistfile1.m

- (void)maskChip {
    UIGraphicsBeginImageContextWithOptions(self.containerView.bounds.size, NO, [UIScreen mainScreen].scale);
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    
    CGRect frame = self.containerView.bounds;
    CGMutablePathRef path = CGPathCreateMutable();
    CGPathMoveToPoint(path, NULL, 0, 0);
    CGPathAddLineToPoint(path, NULL, frame.size.width / 2.f - 6, 0);
    CGPathAddLineToPoint(path, NULL, frame.size.width / 2.f, 6);
    CGPathAddLineToPoint(path, NULL, frame.size.width / 2.f + 6, 0);
    CGPathAddLineToPoint(path, NULL, frame.size.width, 0);
    CGPathAddLineToPoint(path, NULL, frame.size.width, self.view.bounds.size.height);
    CGPathAddLineToPoint(path, NULL, 0, frame.size.height);
    CGPathAddLineToPoint(path, NULL, 0, 0);
    CGPathCloseSubpath(path);
    
    CGContextAddPath(ctx, path);
    CGContextSetFillColorWithColor(ctx, [UIColor blackColor].CGColor);
    CGContextFillPath(ctx);
    
    UIImage *maskImg = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    CGPathRelease(path);
    
    CAShapeLayer *layer = [CAShapeLayer layer];
    layer.contents = (id)maskImg.CGImage;
    layer.frame = frame;
    self.containerView.layer.mask = layer;
}