iOS 18でのタブ切り替え時におけるライフサイクル遅延の原因と対策

final class Tab1ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .red
        title = "タブ1"
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        NSLog("🟥Tab1 - viewWillAppear")
    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        NSLog("🟥Tab1 - viewDidAppear")
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        NSLog("🟥Tab1 - viewWillDisappear")
    }

    override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(animated)
        NSLog("🟥Tab1 - viewDidDisappear")
    }

    override func viewWillLayoutSubviews() {
        super.viewWillLayoutSubviews()
        NSLog("🟥Tab1 - viewWillLayoutSubviews")
    }

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        NSLog("🟥Tab1 - viewDidLayoutSubviews")
    }
}

final class MyTabController: UITabBarController, UITabBarControllerDelegate {
    override func viewDidLoad() {
        super.viewDidLoad()
        NSLog("🟦TabBarController - viewDidLoad")

        delegate = self
    }

    func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
        guard
            let fromView = selectedViewController?.view,
            let toView = viewController.view,
            fromView != toView
        else {
            return false
        }

        UIView.transition(
            from: fromView,
            to: toView,
            duration: 0,
            options: [],
            completion: nil
        )
        return true
    }
}