roundMask.swift

    fileprivate func roundMask() -> CAShapeLayer {
        let px = avatarView.bounds.midX
        let py = avatarView.bounds.midY
        let frame = CGRect(x: -px, y: -py, width: avatarView.bounds.width, height: avatarView.bounds.height)
        let path = UIBezierPath(ovalIn: frame)
        
        let rm = CAShapeLayer()
        
        rm.path = path.cgPath
        rm.fillColor = UIColor.red.cgColor
        rm.position = CGPoint(x: px, y: py)
        rm.transform = CATransform3DMakeScale(0.01, 0.01, 1)
        
        return rm
    }