How to keep a round imageView round using auto layout?

How do I turn a rectangular image view into a circular image view that can hold shape in auto layout without setting width and height restraints? Thereby allowing the imageView to define it’s size, and size bigger and smaller relative to objects around it with leading, trailing, top, and bottom constraints.

I asked a similar question the other day, but I think this might be posed in a more concise way. Thanks so much!

EDIT

Ok, I started over to make this as simple as possible. I have a view named "Cell" and a UIImageView named "dog" within the cell, and that's it. I don't have "unable to simultaneously satisfy constraints" in the console anymore, just two simple views using auto layout. I'm still trying to use this code to round the UIImageView:

profileImageView.layer.cornerRadius = profileImageView.frame.size.width / 2
profileImageView.clipsToBounds = true

Here is the cell constraint setup:

Here is the profile pic constraint setup:

Here is the result without the code, no rounding, but nice and square:

Here is the result with the code to round:

This makes no sense to me, because without the rounding code the image is square, and with the code it's diamond shaped. If it's square shouldn't it be a circle with no issues?

EDIT 2

Here's what happens when I remove the bottom constraint and add a multiplier of .637 for equal height to superview.

Solution 1:

Unfortunately you cannot do this using cornerRadius and autolayout — the CGLayer is not affected by autolayout, so any change in the size of the view will not change the radius which has been set once causing, as you have noticed, the circle to lose its shape.

You can create a custom subclass of UIImageView and override layoutSubviews in order to set the cornerRadius each time the bounds of the imageview change.

EDIT

An example might look something like this:

class Foo: UIImageView {
    override func layoutSubviews() {
        super.layoutSubviews()

        let radius: CGFloat = self.bounds.size.width / 2.0

        self.layer.cornerRadius = radius
    }
}

And obviously you would have to constrain the Foobar instance's width to be the same as the height (to maintain a circle). You would probably also want to set the Foobar instance's contentMode to UIViewContentMode.ScaleAspectFill so that it knows how to draw the image (this means that the image is likely to be cropped).

Solution 2:

Setting radius in viewWillLayoutSubviews will solve the problem

override func viewWillLayoutSubviews() {
  super.viewWillLayoutSubviews()
  profileImageView.layer.cornerRadius = profileImageView.frame.height / 2.0
}