Implementation Idea of rounded corners image view.

AvatarImageView.swift

import UIKit

@IBDesignable class AvatarImageView: UIImageView {
    
    @IBInspectable var shadowRadius: CGFloat = 10.0 {
        didSet {
            setNeedsDisplay()
        }
    }
    @IBInspectable var shadowColor: UIColor = .black {
        didSet {
            setNeedsDisplay()
        }
    }
    
    private var _image: UIImage?
    
    override var image: UIImage? {
        get {
            return _image
        }
        
        set {
            _image = newValue
            
            layer.contents = nil
            contentLayer.contents = newValue?.cgImage
        }
    }
    
    private let shadowLayer = CAShapeLayer()
    private let contentLayer = CALayer()
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        
        layer.insertSublayer(contentLayer, at: 0)
        layer.insertSublayer(shadowLayer, below: contentLayer)
    }
    
    required init?(coder: NSCoder) {
        super.init(coder: coder)
        
        layer.insertSublayer(contentLayer, at: 0)
        layer.insertSublayer(shadowLayer, below: contentLayer)
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        
        contentLayer.frame = bounds
        contentLayer.cornerRadius = bounds.width/2
        contentLayer.masksToBounds = true
        
        shadowLayer.path = UIBezierPath(ovalIn: bounds).cgPath
        shadowLayer.fillColor = UIColor.clear.cgColor
        shadowLayer.shadowColor = UIColor.black.cgColor
        shadowLayer.shadowPath = shadowLayer.path
        shadowLayer.shadowOffset = CGSize(width: 0.0, height: 1.0)
        shadowLayer.shadowOpacity = 0.5
        shadowLayer.shadowRadius = shadowRadius
    }
}