import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?
    var navigationController: UINavigationController?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

        self.window = UIWindow(frame: UIScreen.main.bounds)
        self.window!.makeKeyAndVisible()
        let firstViewController: FirstViewController? = FirstViewController()
        navigationController = UINavigationController(rootViewController: firstViewController!)
        navigationController?.setNavigationBarHidden(true, animated: false)
        window!.rootViewController = navigationController

        return true
    }

    func applicationWillResignActive(_ application: UIApplication) {
    }

    func applicationDidEnterBackground(_ application: UIApplication) {
    }

    func applicationWillEnterForeground(_ application: UIApplication) {
    }

    func applicationDidBecomeActive(_ application: UIApplication) {
    }

    func applicationWillTerminate(_ application: UIApplication) {
    }
}

import UIKit

class CustomButton: UIButton {
    required init(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)!
    }

    override init(frame: CGRect) {
        super.init(frame: frame)
        backgroundColor = UIColor(named: "emerald")
        setTitleColor(UIColor.white, for: UIControl.State.normal)
        titleLabel?.font = UIFont.systemFont(ofSize: 24)
        layer.masksToBounds = false
        layer.cornerRadius = 20.0
        layer.shadowColor = UIColor.lightGray.cgColor
        layer.shadowOffset = CGSize(width: 2.0, height: 2.0)
        layer.shadowOpacity = 0.8
    }
}

import UIKit

class FirstViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        view.backgroundColor = .white
        let buttonHeight: CGFloat = 60

        let button = CustomButton()
        button.frame.size = CGSize(width: view.frame.width * 0.6, height: buttonHeight)
        button.addTarget(self, action: #selector(buttonTaped(sender:)), for: .touchUpInside)
        button.setTitle("Push Me", for: UIControl.State.normal)
        button.center = view.center
        view.addSubview(button)
    }

    @objc func buttonTaped(sender: UIButton) {
        navigationController?.pushViewController(SecondViewController(), animated: true)
    }
}

import UIKit

class SecondViewController: UIViewController {

    var width: CGFloat!
    var height: CGFloat!
    let buttonHeight: CGFloat = 60
    let radius: CGFloat = 100

    var button: CustomButton!

    override func viewDidLoad() {
        super.viewDidLoad()

        view.backgroundColor = .white
        width = view.frame.width
        height = view.frame.height

        //ボタンの生成
        button = CustomButton()
        button.frame.size = CGSize(width: width * 0.6, height: buttonHeight)
        button.center.x = view.frame.width / 2
        button.center.y = view.frame.height / 2 + 40
        button.addTarget(self, action: #selector(cornerCircleButtonClicked(sender:)), for: .touchUpInside)
        button.setTitle("Show Snorlax", for: UIControl.State.normal)
        button.alpha = 0.3
        button.isEnabled = false
        view.addSubview(button)

        // 起動直後のアニメーション
        UIView.animate(withDuration: 0.3, delay: 0.1, options: [.curveLinear], animations: {
                self.button.isEnabled = true
                self.button.alpha = 1.0
                self.button.center = self.view.center
                self.button.frame.size = CGSize(width: self.width * 0.6, height: self.buttonHeight)
            }, completion: nil)
    }

    //角丸ボタンが押されたら呼ばれます
    @objc func cornerCircleButtonClicked(sender: UIButton) {
        button.setTitle("", for: .normal)
        // 丸くするアニメーション
        UIView.animate(withDuration: 0.2, delay: 0.0, options: [.curveLinear], animations: {
                self.button.layer.cornerRadius = self.radius / 2
                self.button.frame.size = CGSize(width: self.radius, height: self.radius)
                self.button.center = self.view.center
            }, completion: { _ in
                //  広がっていくアニメーション
                UIView.animate(withDuration: 0.2, delay: 0.1, options: [.curveLinear], animations: {
                        self.button.layer.cornerRadius = self.width
                        self.button.frame.size = CGSize(width: self.height * 1.5, height: self.height * 1.5)
                        self.button.center = self.view.center
                    }, completion: { _ in
                        self.pushViewController()
                    })
            })
    }

    func pushViewController() {
        // 画面遷移のアニメーション
        let transition = CATransition()
        transition.duration = 0.5
        transition.timingFunction = CAMediaTimingFunction(name: CAMediaTimingFunctionName.easeIn)
        transition.type = CATransitionType.fade
        self.navigationController?.view.layer.add(transition, forKey: nil)
        let viewController = ThirdViewController()
        self.navigationController?.pushViewController(viewController, animated: false)
    }
}

import UIKit

class ThirdViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        
        view.backgroundColor = .white
        let imageView = UIImageView()
        imageView.frame = view.frame
        imageView.image = UIImage(named: "icon")
        view.addSubview(imageView)
    }
}