How to stop an image from stretching within a UIImageView?

Question

I have a UIImageView where I have set the frame size to x = 0, y = 0, width = 404, height = 712. In my project, I need to change the image in

Answer 1

still stretch when image is bigger than imageivew

swift

    let qCodeImage = UIImage(named: "qcode-placeholder.png")!      
    let qCodeImageView = UIImageView(frame: CGRectMake(0, 0, CGRectGetWidth(cardView.frame)-30, CGRectGetWidth(cardView.frame)-30))
    qCodeImageView.image = qCodeImage
    qCodeImageView.clipsToBounds = true
    qCodeImageView.contentMode = UIViewContentMode.ScaleToFill
    qCodeImageView.center = cardView.center