How to use traitCollectionDidChange method of MyViewController class

...348            self.bottomLabel.bottomAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.bottomAnchor),349            self.bottomLabel.centerXAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.centerXAnchor),350            ])351        }352        override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {353          super.traitCollectionDidChange(previousTraitCollection)354          self.topLabel.font = .preferredFont(forTextStyle: .headline, compatibleWith: self.traitCollection)355          self.leadingLabel.font = .preferredFont(forTextStyle: .body, compatibleWith: self.traitCollection)356          self.trailingLabel.font = .preferredFont(forTextStyle: .body, compatibleWith: self.traitCollection)357          self.bottomLabel.font = .preferredFont(forTextStyle: .subheadline, compatibleWith: self.traitCollection)358          self.view.setNeedsUpdateConstraints()359          self.view.updateConstraintsIfNeeded()360        }361      }362      let viewController = MyViewController()363      #if os(iOS)364      assertSnapshot(matching: viewController, as: .image(on: .iPhoneSe), named: "iphone-se")365      assertSnapshot(matching: viewController, as: .image(on: .iPhone8), named: "iphone-8")366      assertSnapshot(matching: viewController, as: .image(on: .iPhone8Plus), named: "iphone-8-plus")367      assertSnapshot(matching: viewController, as: .image(on: .iPhoneX), named: "iphone-x")368      assertSnapshot(matching: viewController, as: .image(on: .iPhoneXr), named: "iphone-xr")369      assertSnapshot(matching: viewController, as: .image(on: .iPhoneXsMax), named: "iphone-xs-max")370      assertSnapshot(matching: viewController, as: .image(on: .iPadMini), named: "ipad-mini")371      assertSnapshot(matching: viewController, as: .image(on: .iPadPro10_5), named: "ipad-pro-10-5")372      assertSnapshot(matching: viewController, as: .image(on: .iPadPro11), named: "ipad-pro-11")373      assertSnapshot(matching: viewController, as: .image(on: .iPadPro12_9), named: "ipad-pro-12-9")374      assertSnapshot(matching: viewController, as: .recursiveDescription(on: .iPhoneSe), named: "iphone-se")375      assertSnapshot(matching: viewController, as: .recursiveDescription(on: .iPhone8), named: "iphone-8")376      assertSnapshot(matching: viewController, as: .recursiveDescription(on: .iPhone8Plus), named: "iphone-8-plus")377      assertSnapshot(matching: viewController, as: .recursiveDescription(on: .iPhoneX), named: "iphone-x")378      assertSnapshot(matching: viewController, as: .recursiveDescription(on: .iPhoneXr), named: "iphone-xr")379      assertSnapshot(matching: viewController, as: .recursiveDescription(on: .iPhoneXsMax), named: "iphone-xs-max")380      assertSnapshot(matching: viewController, as: .recursiveDescription(on: .iPadMini), named: "ipad-mini")381      assertSnapshot(matching: viewController, as: .recursiveDescription(on: .iPadPro10_5), named: "ipad-pro-10-5")382      assertSnapshot(matching: viewController, as: .recursiveDescription(on: .iPadPro11), named: "ipad-pro-11")383      assertSnapshot(matching: viewController, as: .recursiveDescription(on: .iPadPro12_9), named: "ipad-pro-12-9")384      assertSnapshot(matching: viewController, as: .image(on: .iPhoneSe(.portrait)), named: "iphone-se")385      assertSnapshot(matching: viewController, as: .image(on: .iPhone8(.portrait)), named: "iphone-8")386      assertSnapshot(matching: viewController, as: .image(on: .iPhone8Plus(.portrait)), named: "iphone-8-plus")387      assertSnapshot(matching: viewController, as: .image(on: .iPhoneX(.portrait)), named: "iphone-x")388      assertSnapshot(matching: viewController, as: .image(on: .iPhoneXr(.portrait)), named: "iphone-xr")389      assertSnapshot(matching: viewController, as: .image(on: .iPhoneXsMax(.portrait)), named: "iphone-xs-max")390      assertSnapshot(matching: viewController, as: .image(on: .iPadMini(.landscape)), named: "ipad-mini")391      assertSnapshot(matching: viewController, as: .image(on: .iPadPro10_5(.landscape)), named: "ipad-pro-10-5")392      assertSnapshot(matching: viewController, as: .image(on: .iPadPro11(.landscape)), named: "ipad-pro-11")393      assertSnapshot(matching: viewController, as: .image(on: .iPadPro12_9(.landscape)), named: "ipad-pro-12-9")394      assertSnapshot(matching: viewController, as: .image(on: .iPadMini(.landscape(splitView: .oneThird))), named: "ipad-mini-33-split-landscape")395      assertSnapshot(matching: viewController, as: .image(on: .iPadMini(.landscape(splitView: .oneHalf))), named: "ipad-mini-50-split-landscape")396      assertSnapshot(matching: viewController, as: .image(on: .iPadMini(.landscape(splitView: .twoThirds))), named: "ipad-mini-66-split-landscape")397      assertSnapshot(matching: viewController, as: .image(on: .iPadMini(.portrait(splitView: .oneThird))), named: "ipad-mini-33-split-portrait")398      assertSnapshot(matching: viewController, as: .image(on: .iPadMini(.portrait(splitView: .twoThirds))), named: "ipad-mini-66-split-portrait")399      400      assertSnapshot(matching: viewController, as: .image(on: .iPadPro10_5(.landscape(splitView: .oneThird))), named: "ipad-pro-10inch-33-split-landscape")401      assertSnapshot(matching: viewController, as: .image(on: .iPadPro10_5(.landscape(splitView: .oneHalf))), named: "ipad-pro-10inch-50-split-landscape")402      assertSnapshot(matching: viewController, as: .image(on: .iPadPro10_5(.landscape(splitView: .twoThirds))), named: "ipad-pro-10inch-66-split-landscape")403      assertSnapshot(matching: viewController, as: .image(on: .iPadPro10_5(.portrait(splitView: .oneThird))), named: "ipad-pro-10inch-33-split-portrait")404      assertSnapshot(matching: viewController, as: .image(on: .iPadPro10_5(.portrait(splitView: .twoThirds))), named: "ipad-pro-10inch-66-split-portrait")405      406      assertSnapshot(matching: viewController, as: .image(on: .iPadPro11(.landscape(splitView: .oneThird))), named: "ipad-pro-11inch-33-split-landscape")407      assertSnapshot(matching: viewController, as: .image(on: .iPadPro11(.landscape(splitView: .oneHalf))), named: "ipad-pro-11inch-50-split-landscape")408      assertSnapshot(matching: viewController, as: .image(on: .iPadPro11(.landscape(splitView: .twoThirds))), named: "ipad-pro-11inch-66-split-landscape")409      assertSnapshot(matching: viewController, as: .image(on: .iPadPro11(.portrait(splitView: .oneThird))), named: "ipad-pro-11inch-33-split-portrait")410      assertSnapshot(matching: viewController, as: .image(on: .iPadPro11(.portrait(splitView: .twoThirds))), named: "ipad-pro-11inch-66-split-portrait")411      412      assertSnapshot(matching: viewController, as: .image(on: .iPadPro12_9(.landscape(splitView: .oneThird))), named: "ipad-pro-12inch-33-split-landscape")413      assertSnapshot(matching: viewController, as: .image(on: .iPadPro12_9(.landscape(splitView: .oneHalf))), named: "ipad-pro-12inch-50-split-landscape")414      assertSnapshot(matching: viewController, as: .image(on: .iPadPro12_9(.landscape(splitView: .twoThirds))), named: "ipad-pro-12inch-66-split-landscape")415      assertSnapshot(matching: viewController, as: .image(on: .iPadPro12_9(.portrait(splitView: .oneThird))), named: "ipad-pro-12inch-33-split-portrait")416      assertSnapshot(matching: viewController, as: .image(on: .iPadPro12_9(.portrait(splitView: .twoThirds))), named: "ipad-pro-12inch-66-split-portrait")417      418      assertSnapshot(419        matching: viewController, as: .image(on: .iPhoneSe(.landscape)), named: "iphone-se-alternative")420      assertSnapshot(421        matching: viewController, as: .image(on: .iPhone8(.landscape)), named: "iphone-8-alternative")422      assertSnapshot(423        matching: viewController, as: .image(on: .iPhone8Plus(.landscape)), named: "iphone-8-plus-alternative")424      assertSnapshot(425        matching: viewController, as: .image(on: .iPhoneX(.landscape)), named: "iphone-x-alternative")426      assertSnapshot(427        matching: viewController, as: .image(on: .iPhoneXr(.landscape)), named: "iphone-xr-alternative")428      assertSnapshot(429        matching: viewController, as: .image(on: .iPhoneXsMax(.landscape)), named: "iphone-xs-max-alternative")430      assertSnapshot(431        matching: viewController, as: .image(on: .iPadMini(.portrait)), named: "ipad-mini-alternative")432      assertSnapshot(433        matching: viewController, as: .image(on: .iPadPro10_5(.portrait)), named: "ipad-pro-10-5-alternative")434      assertSnapshot(435        matching: viewController, as: .image(on: .iPadPro11(.portrait)), named: "ipad-pro-11-alternative")436      assertSnapshot(437        matching: viewController, as: .image(on: .iPadPro12_9(.portrait)), named: "ipad-pro-12-9-alternative")438      allContentSizes.forEach { name, contentSize in439          assertSnapshot(440            matching: viewController,441            as: .image(on: .iPhoneSe, traits: .init(preferredContentSizeCategory: contentSize)),442            named: "iphone-se-\(name)"443          )444      }445      #elseif os(tvOS)446      assertSnapshot(447        matching: viewController, as: .image(on: .tv), named: "tv")448      #endif449    }450    #endif451  }452  func testTraitsEmbeddedInTabNavigation() {453    #if os(iOS)454    if #available(iOS 11.0, *) {455      class MyViewController: UIViewController {456        let topLabel = UILabel()457        let leadingLabel = UILabel()458        let trailingLabel = UILabel()459        let bottomLabel = UILabel()460        override func viewDidLoad() {461          super.viewDidLoad()462          self.navigationItem.leftBarButtonItem = .init(barButtonSystemItem: .add, target: nil, action: nil)463          self.view.backgroundColor = .white464          self.topLabel.text = "What's"465          self.leadingLabel.text = "the"466          self.trailingLabel.text = "point"467          self.bottomLabel.text = "?"468          self.topLabel.translatesAutoresizingMaskIntoConstraints = false469          self.leadingLabel.translatesAutoresizingMaskIntoConstraints = false470          self.trailingLabel.translatesAutoresizingMaskIntoConstraints = false471          self.bottomLabel.translatesAutoresizingMaskIntoConstraints = false472          self.view.addSubview(self.topLabel)473          self.view.addSubview(self.leadingLabel)474          self.view.addSubview(self.trailingLabel)475          self.view.addSubview(self.bottomLabel)476          NSLayoutConstraint.activate([477            self.topLabel.topAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.topAnchor),478            self.topLabel.centerXAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.centerXAnchor),479            self.leadingLabel.leadingAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.leadingAnchor),480            self.leadingLabel.trailingAnchor.constraint(lessThanOrEqualTo: self.view.safeAreaLayoutGuide.centerXAnchor),481//            self.leadingLabel.trailingAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.centerXAnchor),482            self.leadingLabel.centerYAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.centerYAnchor),483            self.trailingLabel.leadingAnchor.constraint(greaterThanOrEqualTo: self.view.safeAreaLayoutGuide.centerXAnchor),484            self.trailingLabel.trailingAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.trailingAnchor),485            self.trailingLabel.centerYAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.centerYAnchor),486            self.bottomLabel.bottomAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.bottomAnchor),487            self.bottomLabel.centerXAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.centerXAnchor),488            ])489        }490        override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {491          super.traitCollectionDidChange(previousTraitCollection)492          self.topLabel.font = .preferredFont(forTextStyle: .headline, compatibleWith: self.traitCollection)493          self.leadingLabel.font = .preferredFont(forTextStyle: .body, compatibleWith: self.traitCollection)494          self.trailingLabel.font = .preferredFont(forTextStyle: .body, compatibleWith: self.traitCollection)495          self.bottomLabel.font = .preferredFont(forTextStyle: .subheadline, compatibleWith: self.traitCollection)496          self.view.setNeedsUpdateConstraints()497          self.view.updateConstraintsIfNeeded()498        }499      }500      let myViewController = MyViewController()501      let navController = UINavigationController(rootViewController: myViewController)502      let viewController = UITabBarController()503      viewController.setViewControllers([navController], animated: false)504      assertSnapshot(matching: viewController, as: .image(on: .iPhoneSe), named: "iphone-se")505      assertSnapshot(matching: viewController, as: .image(on: .iPhone8), named: "iphone-8")506      assertSnapshot(matching: viewController, as: .image(on: .iPhone8Plus), named: "iphone-8-plus")507      assertSnapshot(matching: viewController, as: .image(on: .iPhoneX), named: "iphone-x")508      assertSnapshot(matching: viewController, as: .image(on: .iPhoneXr), named: "iphone-xr")509      assertSnapshot(matching: viewController, as: .image(on: .iPhoneXsMax), named: "iphone-xs-max")510      assertSnapshot(matching: viewController, as: .image(on: .iPadMini), named: "ipad-mini")511      assertSnapshot(matching: viewController, as: .image(on: .iPadPro10_5), named: "ipad-pro-10-5")512      assertSnapshot(matching: viewController, as: .image(on: .iPadPro11), named: "ipad-pro-11")513      assertSnapshot(matching: viewController, as: .image(on: .iPadPro12_9), named: "ipad-pro-12-9")514      assertSnapshot(matching: viewController, as: .image(on: .iPhoneSe(.portrait)), named: "iphone-se")515      assertSnapshot(matching: viewController, as: .image(on: .iPhone8(.portrait)), named: "iphone-8")516      assertSnapshot(matching: viewController, as: .image(on: .iPhone8Plus(.portrait)), named: "iphone-8-plus")517      assertSnapshot(matching: viewController, as: .image(on: .iPhoneX(.portrait)), named: "iphone-x")518      assertSnapshot(matching: viewController, as: .image(on: .iPhoneXr(.portrait)), named: "iphone-xr")519      assertSnapshot(matching: viewController, as: .image(on: .iPhoneXsMax(.portrait)), named: "iphone-xs-max")520      assertSnapshot(matching: viewController, as: .image(on: .iPadMini(.landscape)), named: "ipad-mini")521      assertSnapshot(matching: viewController, as: .image(on: .iPadPro10_5(.landscape)), named: "ipad-pro-10-5")522      assertSnapshot(matching: viewController, as: .image(on: .iPadPro11(.landscape)), named: "ipad-pro-11")523      assertSnapshot(matching: viewController, as: .image(on: .iPadPro12_9(.landscape)), named: "ipad-pro-12-9")524      assertSnapshot(525        matching: viewController, as: .image(on: .iPhoneSe(.landscape)), named: "iphone-se-alternative")526      assertSnapshot(527        matching: viewController, as: .image(on: .iPhone8(.landscape)), named: "iphone-8-alternative")528      assertSnapshot(529        matching: viewController, as: .image(on: .iPhone8Plus(.landscape)), named: "iphone-8-plus-alternative")530      assertSnapshot(531        matching: viewController, as: .image(on: .iPhoneX(.landscape)), named: "iphone-x-alternative")532      assertSnapshot(533        matching: viewController, as: .image(on: .iPhoneXr(.landscape)), named: "iphone-xr-alternative")534      assertSnapshot(535        matching: viewController, as: .image(on: .iPhoneXsMax(.landscape)), named: "iphone-xs-max-alternative")536      assertSnapshot(537        matching: viewController, as: .image(on: .iPadMini(.portrait)), named: "ipad-mini-alternative")538      assertSnapshot(539        matching: viewController, as: .image(on: .iPadPro10_5(.portrait)), named: "ipad-pro-10-5-alternative")540      assertSnapshot(541        matching: viewController, as: .image(on: .iPadPro11(.portrait)), named: "ipad-pro-11-alternative")542      assertSnapshot(543        matching: viewController, as: .image(on: .iPadPro12_9(.portrait)), named: "ipad-pro-12-9-alternative")544    }545    #endif546  }547  func testCollectionViewsWithMultipleScreenSizes() {548    #if os(iOS)549    final class CollectionViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {550      let flowLayout: UICollectionViewFlowLayout = {551        let layout = UICollectionViewFlowLayout()552        layout.scrollDirection = .horizontal553        layout.minimumLineSpacing = 20554        return layout555      }()556      lazy var collectionView = UICollectionView(frame: .zero, collectionViewLayout: flowLayout)557      override func viewDidLoad() {558        super.viewDidLoad()559        view.backgroundColor = .white560        view.addSubview(collectionView)561        collectionView.backgroundColor = .white562        collectionView.dataSource = self563        collectionView.delegate = self564        collectionView.register(UICollectionViewCell.self, forCellWithReuseIdentifier: "Cell")565        collectionView.translatesAutoresizingMaskIntoConstraints = false566        NSLayoutConstraint.activate([567          collectionView.leadingAnchor.constraint(equalTo: view.layoutMarginsGuide.leadingAnchor),568          collectionView.topAnchor.constraint(equalTo: view.layoutMarginsGuide.topAnchor),569          collectionView.trailingAnchor.constraint(equalTo: view.layoutMarginsGuide.trailingAnchor),570          collectionView.bottomAnchor.constraint(equalTo: view.layoutMarginsGuide.bottomAnchor)571        ])572        collectionView.reloadData()573      }574      override func viewDidLayoutSubviews() {575        super.viewDidLayoutSubviews()576        collectionView.collectionViewLayout.invalidateLayout()577      }578      override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {579        super.traitCollectionDidChange(previousTraitCollection)580        collectionView.collectionViewLayout.invalidateLayout()581      }582      func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {583        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath)584        cell.contentView.backgroundColor = .orange585        return cell586      }587      func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {588        return 20589      }590      func collectionView(591        _ collectionView: UICollectionView,592        layout collectionViewLayout: UICollectionViewLayout,593        sizeForItemAt indexPath: IndexPath...

...50                        self.bottomLabel.centerXAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.centerXAnchor),51                    ])52                }53                54                override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {55                    super.traitCollectionDidChange(previousTraitCollection)56                    self.topLabel.font = .preferredFont(forTextStyle: .headline, compatibleWith: self.traitCollection)57                    self.bottomLabel.font = .preferredFont(forTextStyle: .subheadline, compatibleWith: self.traitCollection)58                    self.view.setNeedsUpdateConstraints()59                    self.view.updateConstraintsIfNeeded()60                }61            }62            63            let myViewController = MyViewController()64            let navController = UINavigationController(rootViewController: myViewController)65            let viewController = UITabBarController()66            viewController.setViewControllers([navController], animated: false)67            68            assertSnapshot(matching: viewController, as: .image(on: .iPhone8), named: "iphone-8")69        }...

...45        46        setNeedsStatusBarAppearanceUpdate()47    }48    49    open override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {50        setNeedsStatusBarAppearanceUpdate()51    }52    53    54}...

1class MyViewController: UIViewController {2    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {3        super.traitCollectionDidChange(previousTraitCollection)4    }5}6class MyViewController: UIViewController {7    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {8        super.traitCollectionDidChange(previousTraitCollection)9    }10}11class MyViewController: UIViewController {12    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {13        super.traitCollectionDidChange(previousTraitCollection)14    }15}16class MyViewController: UIViewController {17    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {18        super.traitCollectionDidChange(previousTraitCollection)19    }20}21class MyViewController: UIViewController {22    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {23        super.traitCollectionDidChange(previousTraitCollection)24    }25}26class MyViewController: UIViewController {27    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {28        super.traitCollectionDidChange(previousTraitCollection)29    }30}31class MyViewController: UIViewController {32    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {33        super.traitCollectionDidChange(previousTraitCollection)34    }35}36class MyViewController: UIViewController {37    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {38        super.traitCollectionDidChange(previousTraitCollection)39    }40}

1class MyViewController: UIViewController {2    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {3        super.traitCollectionDidChange(previousTraitCollection)4    }5}6class MyViewController: UIViewController {7    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {8        super.traitCollectionDidChange(previousTraitCollection)9    }10}11class MyViewController: UIViewController {12    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {13        super.traitCollectionDidChange(previousTraitCollection)14    }15}16class MyViewController: UIViewController {17    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {18        super.traitCollectionDidChange(previousTraitCollection)19    }20}21class MyViewController: UIViewController {22    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {23        super.traitCollectionDidChange(previousTraitCollection)24    }25}26class MyViewController: UIViewController {27    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {28        super.traitCollectionDidChange(previousTraitCollection)29    }30}31class MyViewController: UIViewController {32    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {33        super.traitCollectionDidChange(previousTraitCollection)34    }35}36class MyViewController: UIViewController {37    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {38        super.traitCollectionDidChange(previousTraitCollection)39    }40}41class MyViewController: UIViewController {

1class MyViewController : UIViewController {2    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {3        super.traitCollectionDidChange(previousTraitCollection)4    }5}6class MyViewController : UIViewController {7    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {8        super.traitCollectionDidChange(previousTraitCollection)9    }10}11class MyViewController : UIViewController {12    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {13        super.traitCollectionDidChange(previousTraitCollection)14    }15}16class MyViewController : UIViewController {17    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {18        super.traitCollectionDidChange(previousTraitCollection)19    }20}21class MyViewController : UIViewController {22    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {23        super.traitCollectionDidChange(previousTraitCollection)24    }25}26class MyViewController : UIViewController {27    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {28        super.traitCollectionDidChange(previousTraitCollection)29    }30}31class MyViewController : UIViewController {32    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {33        super.traitCollectionDidChange(previousTraitCollection)34    }35}36class MyViewController : UIViewController {37    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {38        super.traitCollectionDidChange(previousTraitCollection)39    }40}

1class MyViewController: UIViewController {2    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {3        super.traitCollectionDidChange(previousTraitCollection)4    }5}6class MyViewController: UIViewController {7    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {8        super.traitCollectionDidChange(previousTraitCollection)9    }10}11class MyViewController: UIViewController {12    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {13        super.traitCollectionDidChange(previousTraitCollection)14    }15}16class MyViewController: UIViewController {17    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {18        super.traitCollectionDidChange(previousTraitCollection)19    }20}21class MyViewController: UIViewController {22    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {23        super.traitCollectionDidChange(previousTraitCollection)24    }25}26class MyViewController: UIViewController {27    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {28        super.traitCollectionDidChange(previousTraitCollection)29    }30}31class MyViewController: UIViewController {32    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {33        super.traitCollectionDidChange(previousTraitCollection)34    }35}36class MyViewController: UIViewController {37    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {38        super.traitCollectionDidChange(previousTraitCollection)39    }40}

1override func traitCollectionDidChange(previousTraitCollection: UITraitCollection?) {2    super.traitCollectionDidChange(previousTraitCollection)3    print("traitCollectionDidChange")4}5override func traitCollectionDidChange(previousTraitCollection: UITraitCollection?) {6    super.traitCollectionDidChange(previousTraitCollection)7    print("traitCollectionDidChange")8}9override func traitCollectionDidChange(previousTraitCollection: UITraitCollection?) {10    super.traitCollectionDidChange(previousTraitCollection)11    print("traitCollectionDidChange")12}13override func traitCollectionDidChange(previousTraitCollection: UITraitCollection?) {14    super.traitCollectionDidChange(previousTraitCollection)15    print("traitCollectionDidChange")16}17override func traitCollectionDidChange(previousTraitCollection: UITraitCollection?) {18    super.traitCollectionDidChange(previousTraitCollection)19    print("traitCollectionDidChange")20}21override func traitCollectionDidChange(previousTraitCollection: UITraitCollection?) {22    super.traitCollectionDidChange(previousTraitCollection)23    print("traitCollectionDidChange")24}25override func traitCollectionDidChange(previousTraitCollection: UITraitCollection?) {26    super.traitCollectionDidChange(previousTraitCollection)27    print("traitCollectionDidChange")28}29override func traitCollectionDidChange(previousTraitCollection: UITraitCollection?) {30    super.traitCollectionDidChange(previousTraitCollection)31    print("traitCollectionDidChange")32}33override func traitCollectionDidChange(previousTraitCollection: UITraitCollection?) {34    super.traitCollectionDidChange(previousTraitCollection)35    print("traitCollectionDidChange")36}