material-components_material-components-ios/components/Tabs/examples/TabBarIconExample.swift

// Copyright 2016-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.MaterialAppBar
import MaterialComponents.MaterialButtons
import MaterialComponents.MaterialColorScheme
import MaterialComponents.MaterialPalettes
import MaterialComponents.MaterialTabs
import MaterialComponents.MaterialTabs_ColorThemer
import MaterialComponents.MaterialTypographyScheme

class TabBarIconSwiftExample: UIViewController {

  // MARK: Properties
  var alignment: MDCTabBarAlignment {
    get {
      return tabBar.alignment
    }
    set(newAlignment) {
      tabBar.setAlignment(newAlignment, animated: true)
    }
  }

  lazy var alignmentButton: MDCButton = self.setupAlignmentButton()
  lazy var appBarViewController: MDCAppBarViewController = self.setupAppBar()
  lazy var scrollView: UIScrollView = self.setupScrollView()
  lazy var starPage: UIView = self.setupStarPage()
  var colorScheme = MDCSemanticColorScheme()
  var typographyScheme = MDCTypographyScheme()

  lazy var tabBar: MDCTabBar = {
    let tabBar = MDCTabBar()
    tabBar.delegate = self
    tabBar.alignment = .centerSelected

    let bundle = Bundle(for: TabBarIconSwiftExample.self)
    let info = UIImage.init(named: "TabBarDemo_ic_info", in: bundle, compatibleWith:nil)
    let star = UIImage.init(named: "TabBarDemo_ic_star", in: bundle, compatibleWith:nil)

    tabBar.items = [UITabBarItem(title: "Info", image: info, tag:0),
                    UITabBarItem(title: "Stars", image: star, tag:0)]
    tabBar.items[1].badgeValue = "1"

    MDCTabBarColorThemer.applySemanticColorScheme(self.colorScheme, toTabs: tabBar);

    let blue = MDCPalette.blue.tint500
    tabBar.inkColor = blue
    tabBar.itemAppearance = .titledImages

    return tabBar
  }()

  // MARK: Methods
  override func viewDidLoad() {
    super.viewDidLoad()

    setupExampleViews()

    alignmentButton.addTarget(self,
                              action:#selector(changeAlignmentDidTouch(sender:)),
                              for: .touchUpInside)
  }

  @objc func changeAlignmentDidTouch(sender: UIButton) {
    let sheet = UIAlertController(title: nil, message: nil, preferredStyle: .actionSheet)
    sheet.popoverPresentationController?.sourceView = self.alignmentButton
    sheet.popoverPresentationController?.sourceRect = self.alignmentButton.bounds
    sheet.addAction(UIAlertAction(title: "Leading", style: .default, handler: { _ in
      self.alignment = .leading
    }))
    sheet.addAction(UIAlertAction(title: "Center", style: .default, handler: { _ in
      self.alignment = .center
    }))
    sheet.addAction(UIAlertAction(title: "Justified", style: .default, handler: { _ in
      self.alignment = .justified
    }))
    sheet.addAction(UIAlertAction(title: "Selected Center", style: .default, handler: { _ in
      self.alignment = .centerSelected
    }))
    present(sheet, animated: true, completion:nil)
  }

  func incrementStarBadge() {
    let starItem = tabBar.items[1]
    guard let badgeValue = starItem.badgeValue,
      let badgeNumber = Int(badgeValue), badgeNumber > 0 else {
      return
    }

    starItem.badgeValue = NumberFormatter.localizedString(from:(badgeNumber + 1) as NSNumber,
                                                          number: .none)
  }

  // MARK: Action
  @objc func incrementDidTouch(sender: UIBarButtonItem) { incrementStarBadge()

    addStar(centered: false)
  }

}

// MARK: Tab Bar delegate
extension TabBarIconSwiftExample: MDCTabBarDelegate {
  func tabBar(_ tabBar: MDCTabBar, didSelect item: UITabBarItem) {
    guard let index = tabBar.items.index(of: item) else {
      fatalError("MDCTabBarDelegate given selected item not found in tabBar.items")
    }

    scrollView.setContentOffset(CGPoint(x: CGFloat(index) * view.bounds.width, y: 0),
                                animated: true)
  }
}