Extension for cropping an UIImage to a square.

UIImage crop to square

extension UIImage {
    func cropsToSquare() -> UIImage {
        let refWidth = CGFloat(CGImageGetWidth(self.CGImage))
        let refHeight = CGFloat(CGImageGetHeight(self.CGImage))
        let cropSize = refWidth > refHeight ? refHeight : refWidth

        let x = (refWidth - cropSize) / 2.0
        let y = (refHeight - cropSize) / 2.0

        let cropRect = CGRectMake(x, y, cropSize, cropSize)
        let imageRef = CGImageCreateWithImageInRect(self.CGImage, cropRect)
        let cropped = UIImage(CGImage: imageRef, scale: 0.0, orientation: self.imageOrientation)!

        return cropped
    }
}

Doesn't crash when passed a nil image:

extension UIImage {
    func cropsToSquare() -> UIImage? {
        if let image = self.cgImage {
            let refWidth = CGFloat((image.width))
            let refHeight = CGFloat((image.height))
            let cropSize = refWidth > refHeight ? refHeight : refWidth
            
            let x = (refWidth - cropSize) / 2.0
            let y = (refHeight - cropSize) / 2.0
            
            let cropRect = CGRect(x: x, y: y, width: cropSize, height: cropSize)
            let imageRef = image.cropping(to: cropRect)
            let cropped = UIImage(cgImage: imageRef!, scale: 0.0, orientation: self.imageOrientation)
            return cropped
        }
        return nil
    }
}