components/NavigationDrawer/examples/BottomDrawerWithScrollableContentExample.swift

// Copyright 2018-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 UIKit
import MaterialComponents.MaterialBottomAppBar
import MaterialComponents.MaterialNavigationDrawer
import MaterialComponents.MaterialColorScheme

class BottomDrawerWithScrollableContentExample: UIViewController {
  @objc var colorScheme = MDCSemanticColorScheme(defaults: .material201804)
  let bottomAppBar = MDCBottomAppBarView()

  let headerViewController = DrawerHeaderViewController()
  let contentViewController = DrawerContentWithScrollViewController()

  override func viewDidLoad() {
    super.viewDidLoad()
    view.backgroundColor = colorScheme.backgroundColor
    contentViewController.colorScheme = colorScheme

    bottomAppBar.isFloatingButtonHidden = true
    let barButtonLeadingItem = UIBarButtonItem()
    let menuImage = UIImage(named: "system_icons/menu")?.withRenderingMode(.alwaysTemplate)
    barButtonLeadingItem.image = menuImage
    barButtonLeadingItem.target = self
    barButtonLeadingItem.action = #selector(presentNavigationDrawer)
    bottomAppBar.leadingBarButtonItems = [barButtonLeadingItem]

    bottomAppBar.barTintColor = colorScheme.surfaceColor
    let barItemTintColor = colorScheme.onSurfaceColor.withAlphaComponent(0.6)
    bottomAppBar.leadingBarItemsTintColor = barItemTintColor
    bottomAppBar.trailingBarItemsTintColor = barItemTintColor
    bottomAppBar.floatingButton.setBackgroundColor(colorScheme.primaryColor, for: .normal)
    bottomAppBar.floatingButton.setTitleColor(colorScheme.onPrimaryColor, for: .normal)
    bottomAppBar.floatingButton.setImageTintColor(colorScheme.onPrimaryColor, for: .normal)

    view.addSubview(bottomAppBar)
  }

  private func layoutBottomAppBar() {
    let size = bottomAppBar.sizeThatFits(view.bounds.size)
    var bottomBarViewFrame = CGRect(
      x: 0,
      y: view.bounds.size.height - size.height,
      width: size.width,
      height: size.height)
    bottomBarViewFrame.size.height += view.safeAreaInsets.bottom
    bottomBarViewFrame.origin.y -= view.safeAreaInsets.bottom
    bottomAppBar.frame = bottomBarViewFrame
  }

  override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()

    layoutBottomAppBar()
  }

  @objc func presentNavigationDrawer() {
    let bottomDrawerViewController = MDCBottomDrawerViewController()
    bottomDrawerViewController.maximumInitialDrawerHeight = 400
    bottomDrawerViewController.contentViewController = contentViewController
    bottomDrawerViewController.headerViewController = headerViewController
    bottomDrawerViewController.trackingScrollView = contentViewController.collectionView
    bottomDrawerViewController.headerViewController?.view.backgroundColor = colorScheme.surfaceColor
    bottomDrawerViewController.contentViewController?.view.backgroundColor =
      colorScheme.surfaceColor
    bottomDrawerViewController.scrimColor = colorScheme.onSurfaceColor.withAlphaComponent(0.32)
    present(bottomDrawerViewController, animated: true, completion: nil)
  }
}

class DrawerContentWithScrollViewController: UIViewController,
  UICollectionViewDelegate, UICollectionViewDataSource
{
  @objc var colorScheme: MDCSemanticColorScheme!

  let collectionView: UICollectionView
  let layout = UICollectionViewFlowLayout()

  init() {
    collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
    super.init(nibName: nil, bundle: nil)
  }

  required init?(coder aDecoder: NSCoder) {
    collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
    super.init(coder: aDecoder)
  }

  override func viewDidLoad() {
    super.viewDidLoad()
    collectionView.frame = CGRect(
      x: 0, y: 0, width: self.view.bounds.width,
      height: self.view.bounds.height)
    collectionView.register(UICollectionViewCell.self, forCellWithReuseIdentifier: "Cell")
    collectionView.delegate = self
    collectionView.dataSource = self
    collectionView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
    layout.minimumLineSpacing = 0
    layout.minimumInteritemSpacing = 0
    self.view.addSubview(collectionView)
  }

  override func viewWillLayoutSubviews() {
    super.viewWillLayoutSubviews()
    let s = self.view.frame.size.width / 3
    layout.itemSize = CGSize(width: s, height: s)
    self.preferredContentSize = CGSize(
      width: view.bounds.width,
      height: layout.collectionViewContentSize.height)
  }

  func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int)
    -> Int
  {
    return 102
  }

  func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath)
    -> UICollectionViewCell
  {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath)
    let colorPick = indexPath.row % 2 == 0
    cell.backgroundColor = colorPick ? colorScheme.surfaceColor : colorScheme.primaryColorVariant
    return cell
  }

  func numberOfSections(in collectionView: UICollectionView) -> Int {
    return 1
  }
}

extension BottomDrawerWithScrollableContentExample {

  @objc class func catalogMetadata() -> [String: Any] {
    return [
      "breadcrumbs": ["Navigation Drawer", "Bottom Drawer Scrollable Content"],
      "primaryDemo": false,
      "presentable": false,
    ]
  }
}