Know the real bounds of an image in UIImageView

I am usin开发者_运维技巧g an UIImageView to load an image with aspectfit. Hence the image does use the whole UIImageView surface. How to know what is the bounds of the image inside the UIImageView?

Thanks in advance

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CGFloat aspectRatioX = imageView.bounds.size.width/imageView.image.size.width;
CGFloat aspectRatioY = imageView.bounds.size.height/imageView.image.size.height;
if ( aspectRatioX < aspectRatioY )
    imageRect = CGRectMake(0, (imageView.bounds.size.height - aspectRatioX*imageView.image.size.height)*0.5f, imageView.bounds.size.width, aspectRatioX*imageView.image.size.height);
else
    imageRect = CGRectMake((imageView.bounds.size.width - aspectRatioY*imageView.image.size.width)*0.5f, 0, aspectRatioY*imageView.image.size.width, imageView.bounds.size.height);