iOS/Prevent image aspect ratio from changing when resizing - ios

Question

I am using the code below first to create an image thumb (using a category) and then tailor the thumb to the VC in question, for example, make it round.
Somehow, the aspect ratio of images is not getting preserved with some getting squashed vertically...so a face looks like a sideways oval while others get squashed horizontally, so a round ball looks like an upright football. In the code for individual VCs, I am using UIViewContentModeScaleAspectFill and setting clip to bounds to yes but to no avail. Also tried checking these in Storybord but still no luck.
Can anyone see what might be wrong with code below?
//code in viewDidLoad
UIImage *thumbnail = [selectedImage createThumbnailToFillSize:CGSizeMake(side, side)];
//see createThumbNail method below
self.contactImage.image = thumbnail;
//image has been selected and trimmed to thumb. Now format it
CGSize itemSize = CGSizeMake(64, 64);
UIGraphicsBeginImageContextWithOptions(itemSize, NO, UIScreen.mainScreen.scale);
CGRect imageRect = CGRectMake(0.0, 0.0, itemSize.width, itemSize.height);
self.contactImage.contentMode = UIViewContentModeScaleAspectFill;
self.contactImage.clipsToBounds = YES;
[self.contactImage.image drawInRect:imageRect];
self.contactImage.image = UIGraphicsGetImageFromCurrentImageContext();
self.contactImage.layer.cornerRadius=60.0;
UIGraphicsEndImageContext();
//Generic category to create thumb
-(UIImage *) createThumbnailToFillSize:(CGSize)size
{
CGSize mainImageSize = size;
UIImage *thumb;
CGFloat widthScaler = size.width / mainImageSize.width;
CGFloat heightScaler = size.height / mainImageSize.height;
CGSize repositionedMainImageSize = mainImageSize;
CGFloat scaleFactor;
// Determine if we should shrink based on width or hight
if(widthScaler > heightScaler)
{
// calculate based on width scaler
scaleFactor = widthScaler;
repositionedMainImageSize.height = ceil(size.height / scaleFactor);
}
else {
// calculate based on height scaler
scaleFactor = heightScaler;
repositionedMainImageSize.width = ceil(size.width / heightScaler);
}
UIGraphicsBeginImageContext(size);
CGFloat xInc = ((repositionedMainImageSize.width-mainImageSize.width) / 2.f) *scaleFactor;
CGFloat yInc = ((repositionedMainImageSize.height-mainImageSize.height) / 2.f) *scaleFactor;
[self drawInRect:CGRectMake(xInc, yInc, mainImageSize.width * scaleFactor, mainImageSize.height * scaleFactor)];
thumb = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return thumb;
}