stack.playground

//: A UIKit based Playground for presenting user interface

import PlaygroundSupport
import UIKit

class MyViewController: UIViewController {
    let button1 = UIButton()
    let button2 = UIButton()
    let button3 = UIButton()
    let button4 = UIButton()

    let view1 = UIView()
    let view2 = UIView()
    let view3 = UIView()
    let view4 = UIView()

    override func loadView() {
        let view = UIView()
        view.backgroundColor = .gray

        button1.addTarget(self, action: #selector(show1), for: .touchUpInside)
        button1.translatesAutoresizingMaskIntoConstraints = false
        button1.setTitle("show view 1", for: .normal)
        button2.addTarget(self, action: #selector(show2), for: .touchUpInside)
        button2.translatesAutoresizingMaskIntoConstraints = false
        button2.setTitle("show view2", for: .normal)
        button3.addTarget(self, action: #selector(show3), for: .touchUpInside)
        button3.translatesAutoresizingMaskIntoConstraints = false
        button3.setTitle("show view3", for: .normal)
        button4.addTarget(self, action: #selector(show4), for: .touchUpInside)
        button4.translatesAutoresizingMaskIntoConstraints = false
        button4.setTitle("show view4", for: .normal)

        view.addSubview(button1)
        view.addSubview(button2)
        view.addSubview(button3)
        view.addSubview(button4)

        let stack = UIStackView()
        stack.axis = .vertical
        view.addSubview(stack)
        stack.translatesAutoresizingMaskIntoConstraints = false

        view1.backgroundColor = .red
        view1.translatesAutoresizingMaskIntoConstraints = false

        view2.backgroundColor = .green
        view2.translatesAutoresizingMaskIntoConstraints = false
        view2.alpha = 0
        view2.isHidden = true

        view3.backgroundColor = .blue
        view3.translatesAutoresizingMaskIntoConstraints = false
        view3.alpha = 0
        view3.isHidden = true

        view4.backgroundColor = .yellow
        view4.translatesAutoresizingMaskIntoConstraints = false
        view4.alpha = 0
        view4.isHidden = true

        let constraints = [
            button1.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor),
            button1.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            button2.topAnchor.constraint(equalTo: button1.bottomAnchor),
            button2.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            button3.topAnchor.constraint(equalTo: button2.bottomAnchor),
            button3.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            button4.topAnchor.constraint(equalTo: button3.bottomAnchor),
            button4.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            view1.heightAnchor.constraint(equalToConstant: 200),
            view1.widthAnchor.constraint(equalToConstant: 200),
            view2.heightAnchor.constraint(equalToConstant: 100),
            view3.heightAnchor.constraint(equalToConstant: 250),
            view4.heightAnchor.constraint(equalToConstant: 150),
            stack.widthAnchor.constraint(equalToConstant: 250),
            stack.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor),
            stack.centerXAnchor.constraint(equalTo: view.centerXAnchor),
        ]
        NSLayoutConstraint.activate(constraints)

        stack.addArrangedSubview(view1)
        stack.addArrangedSubview(view2)
        stack.addArrangedSubview(view3)
        stack.addArrangedSubview(view4)

        self.view = view
    }

    @objc func show1() {
        animate {
            self.resetSubviews(to: self.view1)
        }
    }

    @objc func show2() {
        animate {
            self.resetSubviews(to: self.view2)
        }
    }

    @objc func show3() {
        animate {
            self.resetSubviews(to: self.view3)
        }
    }

    @objc func show4() {
        animate {
            self.resetSubviews(to: self.view4)
        }
    }

    private func resetSubviews(to view: UIView) {
        view1.alpha = view == view1 ? 1 : 0
        view2.alpha = view == view2 ? 1 : 0
        view3.alpha = view == view3 ? 1 : 0
        view4.alpha = view == view4 ? 1 : 0

        view1.isHidden = view != view1
        view2.isHidden = view != view2
        view3.isHidden = view != view3
        view4.isHidden = view != view4
    }

    func animate(_ actions: @escaping () -> Void) {
        UIView.animate(withDuration: 0.2, animations: {
            actions()
        })
    }
}

// Present the view controller in the Live View window
PlaygroundPage.current.liveView = MyViewController()