material-components_material-components-ios/components/Cards/examples/supplemental/ToggleButtonCell.swift

// Copyright 2019-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.MaterialCards_Theming 

class ToggleButtonCell: MDCCardCollectionCell {

  private lazy var imageView: UIImageView = {
    let imageView = UIImageView(frame: CGRect.zero)
    imageView.contentMode = .scaleAspectFill
    imageView.clipsToBounds = true
    imageView.translatesAutoresizingMaskIntoConstraints = false
    return imageView
  }()

  override init(frame: CGRect) {
    super.init(frame: frame)
    setCustomToggleButton()
  }

  required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
    setCustomToggleButton()
  }

  func setCardImage(named imageName: String) {

    let bundle = Bundle(for: ToggleButtonCell.self)
    imageView.image = UIImage(named: imageName, in: bundle, compatibleWith: nil)
    imageView.contentMode = .scaleAspectFill

    if imageView.superview == nil {
      contentView.addSubview(imageView)
      addConstrains()
    }
  }

  /// Customize the toggle button icon of the cell
  func setCustomToggleButton() {
    // Render the icon images as templates so they can be tinted.
    let bundle = Bundle(for: ToggleButtonCell.self)
    let selectedIcon = UIImage(named: "ic_favorite_24dp", in: bundle, compatibleWith: nil)?
      .withRenderingMode(.alwaysTemplate)
    let unselectedIcon = UIImage(named: "ic_favorite_border_24dp", in: bundle, compatibleWith: nil)?
      .withRenderingMode(.alwaysTemplate)

    // Set the toggle button image and tint color.
    setImage(selectedIcon, for: .selected)
    setImage(unselectedIcon, for: .normal)
  }

  func addConstrains() {
    NSLayoutConstraint.activate([
      contentView.leftAnchor.constraint(equalTo: imageView.leftAnchor),
      contentView.rightAnchor.constraint(equalTo: imageView.rightAnchor),
      contentView.topAnchor.constraint(equalTo: imageView.topAnchor),
      contentView.bottomAnchor.constraint(equalTo: imageView.bottomAnchor),
    ])
  }

  func preiOS11Constraints() {
    imageView.addConstraints(
      NSLayoutConstraint.constraints(
        withVisualFormat: "H:|[view]|",
        options: [],
        metrics: nil,
        views: ["view": contentView]))
    imageView.addConstraints(
      NSLayoutConstraint.constraints(
        withVisualFormat: "V:|[view]|",
        options: [],
        metrics: nil,
        views: ["view": contentView]))
  }
}