material-components_material-components-ios/components/BottomNavigation/examples/BottomNavigationTypicalUseExample.swift

/*
 Copyright 2017-present the Material Components for iOS authors. All Rights Reserved.

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
*/

import Foundation
import MaterialComponents

class BottomNavigationTypicalUseSwiftExample: UIViewController {

  let appBar = MDCAppBar()

  // Create a bottom navigation bar to add to a view.
  let bottomNavBar = MDCBottomNavigationBar()

  init() {
    super.init(nibName: nil, bundle: nil)
    self.title = "Bottom Navigation (Swift)"

    self.addChildViewController(appBar.headerViewController)
    let color = UIColor(white: 0.2, alpha:1)
    appBar.headerViewController.headerView.backgroundColor = color
    appBar.navigationBar.tintColor = .white
    appBar.navigationBar.titleTextAttributes = [NSForegroundColorAttributeName : UIColor.white]

    commonBottomNavigationTypicalUseSwiftExampleInit()
  }

  @available(*, unavailable)
  required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
  }

  func commonBottomNavigationTypicalUseSwiftExampleInit() {
    view.backgroundColor = .lightGray
    view.addSubview(bottomNavBar)

    // Always show bottom navigation bar item titles.
    bottomNavBar.titleVisibility = .always

    // Cluster and center the bottom navigation bar items.
    bottomNavBar.alignment = .centered

    // Theme the bottom navigation bar.
    let scheme = MDCBasicColorScheme(primaryColor: MDCPalette.purple.tint700,
                                     secondaryColor: .white)
    MDCBottomNavigationBarColorThemer.apply(scheme, to: bottomNavBar)

    // Add items to the bottom navigation bar.
    let tabBarItem1 = UITabBarItem(title: "Home", image: UIImage(named: "Home"), tag: 0)
    let tabBarItem2 =
      UITabBarItem(title: "Messages", image: UIImage(named: "Email"), tag: 0)
    let tabBarItem3 =
      UITabBarItem(title: "Favorites", image: UIImage(named: "Favorite"), tag: 0)
    bottomNavBar.items = [ tabBarItem1, tabBarItem2, tabBarItem3 ]

    // Select a bottom navigation bar item.
    bottomNavBar.selectedItem = tabBarItem2;
  }
  
  func layoutBottomNavBar() {
    let size = bottomNavBar.sizeThatFits(view.bounds.size)
    let bottomNavBarFrame = CGRect(x: 0,
                                   y: view.bounds.height - size.height,
                                   width: size.width,
                                   height: size.height)
    bottomNavBar.frame = bottomNavBarFrame
  }

  override func viewWillLayoutSubviews() {
    super.viewWillLayoutSubviews()
    layoutBottomNavBar()
  }

  #if swift(>=3.2)
  @available(iOS 11, *)
  override func viewSafeAreaInsetsDidChange() {
    super.viewSafeAreaInsetsDidChange()
    layoutBottomNavBar()
  }
  #endif

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

  override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    self.navigationController?.setNavigationBarHidden(true, animated: animated)
  }
}

// MARK: Catalog by convention
extension BottomNavigationTypicalUseSwiftExample {
  class func catalogBreadcrumbs() -> [String] {
    return ["Bottom Navigation", "Bottom Navigation (Swift)"]
  }

  class func catalogIsPrimaryDemo() -> Bool {
    return false
  }

  func catalogShouldHideNavigation() -> Bool {
    return true
  }

  @objc class func catalogIsPresentable() -> Bool {
    return true
  }
}