material-components_material-components-ios/components/NavigationBar/examples/NavigationBarTypicalUseExample.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.MaterialNavigationBar_ColorThemer
import MaterialComponents.MaterialPalettes

open class NavigationBarTypicalUseSwiftExample: UIViewController {

  var navBar = MDCNavigationBar()
  var colorScheme = MDCSemanticColorScheme()
  var exampleView = ExampleInstructionsViewNavigationBarTypicalUseSwift()

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

    title = "Navigation Bar (Swift)"

    navBar = MDCNavigationBar()
    navBar.observe(navigationItem)

    let mutator = MDCNavigationBarTextColorAccessibilityMutator()
    mutator.mutate(navBar)

    MDCNavigationBarColorThemer.applySemanticColorScheme(colorScheme, to: navBar)

    view.addSubview(navBar)

    navBar.translatesAutoresizingMaskIntoConstraints = false

    #if swift(>=3.2)
      if #available(iOS 11.0, *) {
        self.view.safeAreaLayoutGuide.topAnchor.constraint(equalTo: self.navBar.topAnchor).isActive = true
      } else {
        NSLayoutConstraint(item: self.topLayoutGuide,
                           attribute: .bottom,
                           relatedBy: .equal,
                           toItem: self.navBar,
                           attribute: .top,
                           multiplier: 1,
                           constant: 0).isActive = true
      }
    #else
      NSLayoutConstraint(item: self.topLayoutGuide,
                         attribute: .bottom,
                         relatedBy: .equal,
                         toItem: self.navBar,
                         attribute: .top,
                         multiplier: 1,
                         constant: 0).isActive = true
    #endif

    let viewBindings = ["navBar": navBar]

    NSLayoutConstraint.activate(NSLayoutConstraint.constraints(withVisualFormat: "H:|[navBar]|",
                                                                options: [],
                                                                metrics: nil,
                                                                views: viewBindings))
    self.setupExampleViews()
  }

  func setupExampleViews() {
    /// Both self.viewDidLoad() and super.viewDidLoad() will add NavigationBars to the hierarchy.
    /// We only want to keep one.

    for subview in view.subviews {
      if let navBarSubview = subview as? MDCNavigationBar, navBarSubview != self.navBar {
        navBarSubview.removeFromSuperview()
      }
    }

    exampleView.frame = self.view.bounds
    self.view.insertSubview(exampleView, belowSubview: navBar)
    exampleView.translatesAutoresizingMaskIntoConstraints = false
    let viewBindings: [String : Any] = [ "exampleView" : exampleView, "navBar" : navBar ]
    var constraintsArray: [NSLayoutConstraint] = []
    constraintsArray += NSLayoutConstraint.constraints(withVisualFormat: "H:|[exampleView]|",
                                                         options: [],
                                                         metrics: nil,
                                                         views: viewBindings)
    constraintsArray += NSLayoutConstraint.constraints(withVisualFormat: "V:[navBar]-[exampleView]|",
                                                       options: [],
                                                       metrics: nil,
                                                       views: viewBindings)
    view.addConstraints(constraintsArray)
  }

  override open func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    self.navigationController?.setNavigationBarHidden(true, animated: animated)
  }

  override open var prefersStatusBarHidden: Bool {
    return true
  }

  open override func willAnimateRotation(to toInterfaceOrientation: UIInterfaceOrientation, duration: TimeInterval) {
    exampleView.setNeedsDisplay()
  }
}

class ExampleInstructionsViewNavigationBarTypicalUseSwift: UIView {
  override func draw(_ rect: CGRect) {
    UIColor.white.setFill()
    UIBezierPath(rect: rect).fill()
    let textSizeRect = textSize(forRect: rect)
    let rectForText = CGRect(x: rect.origin.x + rect.size.width / 2 - textSizeRect.width / 2,
                             y: rect.origin.y + rect.size.height / 2 - textSizeRect.height / 2,
                             width: textSizeRect.width,
                             height: textSizeRect.height)
    instructionsString().draw(in: rectForText)
    drawArrow(withFrame: CGRect(x: rect.size.width / 2 - 12,
                                y: rect.size.height / 2 - 58 - 12,
                                width: 24,
                                height: 24))
  }

  func textSize(forRect rect: CGRect) -> CGSize {
    return instructionsString()
      .boundingRect(with: rect.size,
                    options: NSStringDrawingOptions.usesLineFragmentOrigin,
                    context: nil).size
  }

  func instructionsString() -> NSAttributedString {
    let style = NSMutableParagraphStyle()
    style.alignment = .center
    style.lineBreakMode = .byWordWrapping
    let instructionsDictionary1 = [
      NSFontAttributeName : UIFont.preferredFont(forTextStyle: .headline),
      NSForegroundColorAttributeName : MDCPalette.grey.tint600.withAlphaComponent(0.87),
      NSParagraphStyleAttributeName : style
    ]
    let instructionsDictionary2 = [
      NSFontAttributeName : UIFont.preferredFont(forTextStyle: .subheadline),
      NSForegroundColorAttributeName : MDCPalette.grey.tint600.withAlphaComponent(0.87),
      NSParagraphStyleAttributeName : style
    ]
    let instructionText = "SWIPE RIGHT\n\n\nfrom left edge to go back\n\n\n\n\n"
    let instructionsAttributedString = NSMutableAttributedString(string: instructionText)
    instructionsAttributedString.addAttributes(instructionsDictionary1,
                                               range: NSMakeRange(0, 11))
    let endLength = instructionText.characters.count - 11
    instructionsAttributedString.addAttributes(instructionsDictionary2,
                                               range: NSMakeRange(11, endLength))
    return instructionsAttributedString
  }

  func drawArrow(withFrame frame: CGRect) {
    let bezierPath = UIBezierPath()
    bezierPath.move(to: CGPoint(x: frame.origin.x + 12, y: frame.origin.y + 4))
    bezierPath.addLine(to: CGPoint(x: frame.origin.x + 10.59, y: frame.origin.y + 5.41))
    bezierPath.addLine(to: CGPoint(x: frame.origin.x + 16.17, y: frame.origin.y + 11))
    bezierPath.addLine(to: CGPoint(x: frame.origin.x + 4, y: frame.origin.y + 11))
    bezierPath.addLine(to: CGPoint(x: frame.origin.x + 4, y: frame.origin.y + 13))
    bezierPath.addLine(to: CGPoint(x: frame.origin.x + 16.17, y: frame.origin.y + 13))
    bezierPath.addLine(to: CGPoint(x: frame.origin.x + 10.59, y: frame.origin.y + 18.59))
    bezierPath.addLine(to: CGPoint(x: frame.origin.x + 12, y: frame.origin.y + 20))
    bezierPath.addLine(to: CGPoint(x: frame.origin.x + 20, y: frame.origin.y + 12))
    bezierPath.addLine(to: CGPoint(x: frame.origin.x + 12, y: frame.origin.y + 4))
    bezierPath.close()
    bezierPath.miterLimit = 4
    MDCPalette.grey.tint600.withAlphaComponent(0.87).setFill()
    bezierPath.fill()
  }
}