在UIImage上绘制边框和阴影

import UIKit

class CustomImageView: UIImageView {
    override func awakeFromNib() {
        super.awakeFromNib()
        layer.borderWidth = 2.0
        layer.borderColor = UIColor.black.cgColor
        layer.shadowColor = UIColor.black.cgColor
        layer.shadowOpacity = 0.5
        layer.shadowOffset = CGSize(width: 0, height: 2)
        layer.shadowRadius = 2.0
    }
}

let customImageView = CustomImageView(image: UIImage(named: "example"))
view.addSubview(customImageView)