// Returns largest possible centered cropped image.
- (UIImage *)centerCropImage:(UIImage *)image
{
    // Use smallest side length as crop square length
    CGFloat squareLength = MIN(image.size.width, image.size.height);
    // Center the crop area
    CGRect clippedRect = CGRectMake((image.size.width - squareLength) / 2, (image.size.height - squareLength) / 2, squareLength, squareLength);

    // Crop logic
    CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], clippedRect);
    UIImage * croppedImage = [UIImage imageWithCGImage:imageRef];
    CGImageRelease(imageRef);
    return croppedImage;
}

let imageView = UIImageView(image: image)
imageView.contentMode = .scaleAspectFill
imageView.clipsToBounds = true

self.imageView.contentMode = UIViewContentModeScaleAspectFill;
[self.imageView setClipsToBounds:YES];
[self.imageView setImage:img];

- (void)drawMaskLineSegmentTo:(CGPoint)ptTo withMaskWidth:(CGFloat)maskWidth inContext:(NXMaskDrawContext)context{
       if (context == nil)
            return;
       if (context.count <= 0){
            [context addObject:[NSValue valueWithCGPoint:ptTo]];
            return;
       }
       CGPoint ptFrom = [context.lastObject CGPointValue];
       UIGraphicsBeginImageContext(self.maskImage.size);
       [self.maskImage drawInRect:CGRectMake(0, 0, self.maskImage.size.width, self.maskImage.size.height)];
       CGContextRef graphicsContext = UIGraphicsGetCurrentContext();
       CGContextSetBlendMode(graphicsContext, kCGBlendModeCopy);
       CGContextSetRGBStrokeColor(graphicsContext, 1, 1, 1, 1);
       CGContextSetLineWidth(graphicsContext, maskWidth);
       CGContextSetLineCap(graphicsContext, kCGLineCapRound);
       CGContextMoveToPoint(graphicsContext, ptFrom.x, ptFrom.y);
       CGContextAddLineToPoint(graphicsContext, ptTo.x, ptTo.y);
       CGContextStrokePath(graphicsContext);
       self.maskImage = UIGraphicsGetImageFromCurrentImageContext();
       UIGraphicsEndImageContext();

       UIGraphicsBeginImageContext(self.displayableMaskImage.size);
       [self.displayableMaskImage drawInRect:CGRectMake(0, 0, self.displayableMaskImage.size.width, self.displayableMaskImage.size.height)];
       graphicsContext = UIGraphicsGetCurrentContext();
       CGContextSetBlendMode(graphicsContext, kCGBlendModeCopy);
       CGContextSetStrokeColorWithColor(graphicsContext, self.displayableMaskColor.CGColor);
       CGContextSetLineWidth(graphicsContext, maskWidth);
       CGContextSetLineCap(graphicsContext, kCGLineCapRound);
       CGContextMoveToPoint(graphicsContext, ptFrom.x, ptFrom.y);
       CGContextAddLineToPoint(graphicsContext, ptTo.x, ptTo.y);
       CGContextStrokePath(graphicsContext);
       self.displayableMaskImage = UIGraphicsGetImageFromCurrentImageContext();
       UIGraphicsEndImageContext();
       [context addObject:[NSValue valueWithCGPoint:ptTo]];
}