Boat com sobra do Luan

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var button : UIButton!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        button.setShadowStyle()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

}



extension UIButton {
    func setShadowStyle() {
        self.addTarget(self, action: #selector(pressUnshadowEffect), for: UIControlEvents.touchDown)
        self.addTarget(self, action: #selector(pressShadowEffect), for: UIControlEvents.touchUpInside)
        self.shadeButton()
    }

    func shadeButton() {
        self.layer.shadowOffset = CGSize(width: 0, height: 0)
        self.layer.shadowColor = UIColor.black.cgColor
        self.layer.shadowOpacity = 1.0
        self.layer.shadowRadius = 3.0
        self.layer.masksToBounds = false
    }

    func unshadeButton() {
        self.layer.shadowOffset = CGSize(width: 0, height: 0)
        self.layer.shadowColor = UIColor.clear.cgColor
        self.layer.shadowOpacity = 0.0
        self.layer.shadowRadius = 0.0
        self.layer.masksToBounds = false
    }

    @objc func pressShadowEffect() {
        UIView.performWithoutAnimation { [unowned self] in
            self.shadeButton()
        }
    }

    @objc func pressUnshadowEffect() {
        UIView.performWithoutAnimation { [unowned self] in
            self.unshadeButton()
        }
    }
}