Swift: Circumscribed and inscribed circles of a rect (and oval outside rect)

circles.swift

extension CGFloat {
    func radians() -> CGFloat {
        let b = CGFloat(M_PI) * (self/180)
        return b
    }
}

extension UIBezierPath {
    
        convenience init(circumscribedCircleRect rect:CGRect) {
        let halfWidth = rect.width / 2
        let halfHeight = rect.height / 2
        let radius = sqrt(halfWidth * halfWidth + halfHeight * halfHeight)
        let center = CGPointMake(rect.midX, rect.midY)
        self.init(arcCenter: center, radius: radius, startAngle: CGFloat(0).radians(), endAngle: CGFloat(360).radians(), clockwise: true)
    }

    
    convenience init(inscribedCircleRect rect:CGRect) {
        let halfWidth = rect.width / 2
        let halfHeight = rect.height / 2
        let radius = halfWidth >= halfHeight ? halfHeight : halfWidth
        let center = CGPointMake(rect.midX, rect.midY)
        self.init(arcCenter: center, radius: radius, startAngle: CGFloat(0).radians(), endAngle: CGFloat(360).radians(), clockwise: true)
    }
    
    convenience init(ovalOutsideRect rect:CGRect) {
        let width = rect.width
        let height = rect.height
        let origin = CGPointMake(rect.minX, rect.minY)
        let newSize = CGSizeMake(CGFloat(M_SQRT2) * width, CGFloat(M_SQRT2) * height)
        let newRect = CGRect(x: origin.x + (width - newSize.width) / 2, y: origin.y + (height - newSize.height) / 2, width: newSize.width, height: newSize.height)
        self.init(ovalInRect:newRect)
    }
    
}

One use for this might be the masking of an image regardless of whether it is inside a view that is rectangular or square.

// image view code
let imgView = UIImageView(image: UIImage(named: "fish.jpg"))
view.addSubview(imgView)

// positioning code
imgView.centerXAnchor.constraintEqualToAnchor(view.centerXAnchor).active = true
imgView.centerYAnchor.constraintEqualToAnchor(view.centerYAnchor).active = true
imgView.translatesAutoresizingMaskIntoConstraints = false

// masking code
let layerRect = imgView.frame
let maskingBez = UIBezierPath(inscribedCircleRect: layerRect)
let maskingLayer = CAShapeLayer()
maskingLayer.path = maskingBez.CGPath

imgView.layer.mask = maskingLayer