How to make a circular UIView

I want to make a UIView or UIImageView that is a circle. Or a circle that i can change the size of using a slider, and the color of with a pickerview.

As mentioned in some comments, @IBDesignable makes this much easier now, so you can use Interface Builder to configure your rounded UIImageView.

First create a class named RoundedImageView.swift and paste this code to it:

import UIKit

@IBDesignable public class RoundedImageView: UIImageView {

    override public func layoutSubviews() {
        super.layoutSubviews()

        //hard-coded this since it's always round
        layer.cornerRadius = 0.5 * bounds.size.width
    }
}

Select the UIImageView in InterfaceBuilder and change the class from UIImageView to the custom RoundedImageView:

Set Clip to Bounds to true (or the pic will extend beyond the circle):

It should now round itself right there in InterfaceBuilder, which is pretty nifty. Be sure to set the width and height to the same values or it'll be shaped like a zeppelin!