-(CGPathRef)getCGPath:(CGFloat)viewWidth{
 UIBezierPath * path = [UIBezierPath bezierPath];
 path.lineWidth = 2;
 [[UIColor whiteColor] setStroke];
 [path moveToPoint:CGPointMake((sin(M_1_PI / 180 * 60)) * (viewWidth / 2), (viewWidth / 4))];
 [path addLineToPoint:CGPointMake((viewWidth / 2), 0)];
 [path addLineToPoint:CGPointMake(viewWidth - ((sin(M_1_PI / 180 * 60)) * (viewWidth / 2)), (viewWidth / 4))];
 [path addLineToPoint:CGPointMake(viewWidth - ((sin(M_1_PI / 180 * 60)) * (viewWidth / 2)), (viewWidth / 2) + (viewWidth / 4))];
 [path addLineToPoint:CGPointMake((viewWidth / 2), viewWidth)];
 [path addLineToPoint:CGPointMake((sin(M_1_PI / 180 * 60)) * (viewWidth / 2), (viewWidth / 2) + (viewWidth / 4))];
 [path closePath];
 return path.CGPath;
}

 CGRect hexagnoRect = self.bounds;
 //绘制一个六边形的layer，并复制一个image给他的contents
 CALayer *hexagonLayer = [CALayer layer];
 hexagonLayer.frame = hexagnoRect;
 CAShapeLayer * shapLayer = [CAShapeLayer layer];
 shapLayer.lineWidth = 1;
 shapLayer.strokeColor = [UIColor whiteColor].CGColor;
 shapLayer.path = [self getCGPath:hexagnoRect.size.width-20];
 hexagonLayer.mask = shapLayer;
 hexagonLayer.contents = (__bridge id _Nullable)(self.image.CGImage);

 CALayer *completeLayer = [CALayer layer];
 completeLayer.frame = CGRectMake(10, 10, self.bounds.size.width-10, self.bounds.size.height-10);
 [completeLayer addSublayer:hexagonLayer];
 completeLayer.shadowOpacity = 1.0f;
 completeLayer.shadowPath = [self getCGPath:hexagnoRect.size.width];
 completeLayer.shadowOffset = CGSizeMake(-10, -10);

 completeLayer.shadowColor = self.hg_shadowColor.CGColor;
 [self.layer addSublayer:completeLayer];