components/List/examples/BaseCellExample.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 Foundation

class BaseCellExample : UIViewController {
  private let arbitraryCellHeight: CGFloat = 75
  fileprivate let baseCellIdentifier: String = "baseCellIdentifier"
  fileprivate let numberOfCells: Int = 100

  private lazy var collectionView: UICollectionView = {
    return UICollectionView(frame: .zero, collectionViewLayout: UICollectionViewFlowLayout())
  }()

  private var collectionViewLayout: UICollectionViewFlowLayout {
    return collectionView.collectionViewLayout as! UICollectionViewFlowLayout
  }

  private var collectionViewEstimatedCellSize: CGSize {
    return CGSize(width: collectionView.bounds.size.width - 20,
                  height: arbitraryCellHeight)
  }

  override func viewDidLoad() {
    super.viewDidLoad()
    parent?.automaticallyAdjustsScrollViewInsets = false
    automaticallyAdjustsScrollViewInsets = false
    setUpCollectionView()
  }

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

  func setUpCollectionView() {
    collectionViewLayout.estimatedItemSize = collectionViewEstimatedCellSize
    collectionViewLayout.minimumInteritemSpacing = 5
    collectionViewLayout.minimumLineSpacing = 5
    collectionView.backgroundColor = .white
    collectionView.register(MDCBaseCell.self, forCellWithReuseIdentifier: baseCellIdentifier)
    collectionView.delegate = self
    collectionView.dataSource = self
    view.addSubview(collectionView)
  }

  func positionCollectionView() {
    var originX = view.bounds.origin.x
    var originY = view.bounds.origin.y
    var width = view.bounds.size.width
    var height = view.bounds.size.height

    #if swift(>=3.2)
    if #available(iOS 11.0, *) {
      originX += view.safeAreaInsets.left
      originY += view.safeAreaInsets.top
      width -= (view.safeAreaInsets.left + view.safeAreaInsets.right)
      height -= (view.safeAreaInsets.top + view.safeAreaInsets.bottom)
    }
    #endif

    let frame = CGRect(x: originX, y: originY, width: width, height: height);
    collectionView.frame = frame
    collectionViewLayout.estimatedItemSize = collectionViewEstimatedCellSize
    collectionViewLayout.invalidateLayout()
    collectionView.reloadData()
  }
}

extension BaseCellExample: UICollectionViewDelegate {
  func collectionView(_ collectionView: UICollectionView, didHighlightItemAt indexPath: IndexPath) {
    guard let cell = collectionView.cellForItem(at: indexPath) as? MDCBaseCell else { fatalError() }
    cell.elevation = ShadowElevation(rawValue: 10)
  }

  func collectionView(_ collectionView: UICollectionView,
                      didUnhighlightItemAt indexPath: IndexPath) {
    guard let cell = collectionView.cellForItem(at: indexPath) as? MDCBaseCell else { fatalError() }
    cell.elevation = ShadowElevation(rawValue: 0)
  }
}

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

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

  func collectionView(_ collectionView: UICollectionView,
                      cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    guard let cell = collectionView.dequeueReusableCell(withReuseIdentifier: baseCellIdentifier,
                                                        for: indexPath) as? MDCBaseCell
      else { fatalError() }
    cell.layer.borderColor = UIColor.darkGray.cgColor
    cell.layer.borderWidth = 1
    cell.inkColor = UIColor(red: 0, green: 0, blue: 0, alpha: 0.1)
    return cell
  }
}

// MARK: Catalog By Convention
extension BaseCellExample {
  @objc class func catalogBreadcrumbs() -> [String] {
    return ["List Items", "MDCBaseCell Example (Swift)"]
  }

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

  @objc class func catalogDescription() -> String {
    return "MDCBaseCell Example (Swift)"
  }

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

  @objc class func catalogIsDebug() -> Bool {
    return false
  }
}