【Xcode/Swift】XLPagerTabStripとCHIPageControlを使っておしゃれな遷移をさせてみる

import UIKit

extension UIViewController {
    func insertContainerViewController(_ viewController: UIViewController?, to targetView: UIView?, at index: Int) {
        guard let targetView = targetView else { return }
        guard let viewController = viewController else { return }
        guard !children.contains(viewController) else { return }
        viewController.view.frame = targetView.bounds
        addChild(viewController)
        targetView.insertSubview(viewController.view, at: index)
        viewController.didMove(toParent: self)
        targetView.layoutIfNeeded()
    }

}

import UIKit

final class MainViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        showTabViewController()
    }

    func showTabViewController() {
        let controller = TabViewController()
        insertContainerViewController(controller, to: view, at: 0)
    }

}

import UIKit
import XLPagerTabStrip
import CHIPageControl

class TabViewController: PagerTabStripViewController, PagerTabStripDataSource, PagerTabStripIsProgressiveDelegate {

    @IBOutlet private weak var pageControl: CHIPageControlAleppo!

    private lazy var menuViewControllers: [UIViewController] = {
        // FirstView
        let firstViewController = FirstViewController()
        // SecondView
        let secondViewController = SecondViewController()
        // ThirdView
        let thirdViewController = ThirdViewController()
        // ForthView
        let forthViewController = ForthViewController()

        return [firstViewController, secondViewController, thirdViewController, forthViewController]
    }()

    override func viewDidLoad() {
        delegate = self
        datasource = self
        containerView.contentInsetAdjustmentBehavior = .never
        super.viewDidLoad()
        containerView.bounces = false
        containerView.alwaysBounceHorizontal = false
    }

    override func viewControllers(for pagerTabStripController: PagerTabStripViewController) -> [UIViewController] {
        return menuViewControllers
    }

    func updateIndicator(for viewController: PagerTabStripViewController, fromIndex: Int, toIndex: Int) {}

    func updateIndicator(for viewController: PagerTabStripViewController, fromIndex: Int, toIndex: Int, withProgressPercentage progressPercentage: CGFloat, indexWasChanged: Bool) {
        guard fromIndex != toIndex else {
            setNeedsStatusBarAppearanceUpdate()
            return
        }
        let isForward = (fromIndex < toIndex)
        pageControl.progress = Double(fromIndex) + ((isForward) ? Double(progressPercentage) : -Double(progressPercentage))
        guard indexWasChanged else { return }
        setNeedsStatusBarAppearanceUpdate()
        switch toIndex {
        case 0:
            print("DEBUG_PRINT: This is FirstView")
        case 1:
            print("DEBUG_PRINT: This is SecondView")
        case 2:
            print("DEBUG_PRINT: This is ThirdView")
        case 3:
            print("DEBUG_PRINT: This is ForthView")
        default:
            break
        }
    }

}

import UIKit
import XLPagerTabStrip

class <#何番目の#>ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
    }

}

extension <#何番目の#>ViewController: IndicatorInfoProvider {
    func indicatorInfo(for pagerTabStripController: PagerTabStripViewController) -> IndicatorInfo {
        return IndicatorInfo(title: nil)
    }
}