ios/chrome/browser/ui/incognito_interstitial/incognito_interstitial_view_controller.mm - chromium/src - Git at Google

 // Copyright 2022 The Chromium Authors
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #import "ios/chrome/browser/ui/incognito_interstitial/incognito_interstitial_view_controller.h"

 #import <algorithm>

 #import "base/apple/foundation_util.h"
 #import "base/check.h"
 #import "base/ios/ios_util.h"
 #import "ios/chrome/browser/shared/public/features/features.h"
 #import "ios/chrome/browser/shared/ui/elements/extended_touch_target_button.h"
 #import "ios/chrome/browser/shared/ui/util/attributed_string_util.h"
 #import "ios/chrome/browser/shared/ui/util/uikit_ui_util.h"
 #import "ios/chrome/browser/ui/incognito_interstitial/incognito_interstitial_constants.h"
 #import "ios/chrome/browser/ui/ntp/incognito/incognito_view.h"
 #import "ios/chrome/browser/ui/ntp/incognito/revamped_incognito_view.h"
 #import "ios/chrome/common/button_configuration_util.h"
 #import "ios/chrome/common/ui/colors/semantic_color_names.h"
 #import "ios/chrome/common/ui/util/constraints_ui_util.h"
 #import "ios/chrome/grit/ios_strings.h"
 #import "ui/base/device_form_factor.h"
 #import "ui/base/l10n/l10n_util_mac.h"

 namespace {

 // Opacity of navigation bar should be 0% at offset keyframe 0 and 100% at
 // keyframe 1.
 const CGFloat kNavigationBarFadeInKeyFrame0 = 70;
 const CGFloat kNavigationBarFadeInKeyFrame1 = 140;
 const CGFloat kNavigationBarFadeInCompactHeightKeyFrame0 = 20;
 const CGFloat kNavigationBarFadeInCompactHeightKeyFrame1 = 50;

 // Name of banner at the top of the view.
 NSString* const kIncognitoInterstitialBannerName =
     @"incognito_interstitial_screen_banner";

 // Maximum number of lines for the URL label, before the user unfolds it.
 const int kURLLabelDefaultNumberOfLines = 3;

 // Line height multiple for the title label.
 const CGFloat kTitleLabelLineHeightMultiple = 1.3;

 }  // namespace

 @interface IncognitoInterstitialViewController ()

 // The navigation bar to display at the top of the view, to contain a "Cancel"
 // button.
 @property(nonatomic, strong) UINavigationBar* navigationBar;

 // Vertical offset of internal scroll view, to update navigation bar opacity.
 @property(nonatomic, assign) CGFloat scrollViewContentOffsetY;

 // Label to display the URL which is going to be opened.
 @property(nonatomic, strong) UILabel* URLLabel;

 // Button which allows the user to remove the limit on the number of lines
 // for `URLLabel`.
 @property(nonatomic, strong) UIButton* expandURLButton;

 // Whether the number of lines of `URLLabel` is unlimited.
 @property(nonatomic, assign) BOOL URLIsExpanded;

 @end

 @implementation IncognitoInterstitialViewController

 @dynamic delegate;

 #pragma mark - UIViewController

 - (void)viewDidLoad {
   self.view.accessibilityIdentifier =
       kIncognitoInterstitialAccessibilityIdentifier;

   self.bannerName = kIncognitoInterstitialBannerName;
   self.bannerSize = BannerImageSizeType::kStandard;
   self.shouldBannerFillTopSpace = YES;
   self.shouldHideBanner = IsCompactHeight(self.traitCollection);

   NSString* title =
       l10n_util::GetNSString(IDS_IOS_INCOGNITO_INTERSTITIAL_TITLE);
   self.title = title;
   self.titleText = title;
   self.titleHorizontalMargin = 0;
   self.primaryActionString = l10n_util::GetNSString(
       IDS_IOS_INCOGNITO_INTERSTITIAL_OPEN_IN_CHROME_INCOGNITO);
   self.secondaryActionString =
       l10n_util::GetNSString(IDS_IOS_INCOGNITO_INTERSTITIAL_OPEN_IN_CHROME);

   // This needs to be called after parameters of `PromoStyleViewController` have
   // been set, but before adding additional layout constraints, since these
   // constraints can only be activated once the complete view hierarchy has been
   // constructed and relevant views belong to the same hierarchy.
   [super viewDidLoad];

   // Fix the line height multiple of `self.titleLabel`.
   [self fixTitleLabelLineHeightMultiple];

   self.overrideUserInterfaceStyle = UIUserInterfaceStyleDark;
   self.modalInPresentation = YES;

   // Creating the Incognito view (same one as NTP).
   UIScrollView* incognitoView = NULL;
   if (base::FeatureList::IsEnabled(kIncognitoNtpRevamp)) {
     RevampedIncognitoView* revampedIncognitoView =
         [[RevampedIncognitoView alloc] initWithFrame:CGRectZero
                        showTopIncognitoImageAndTitle:NO
                            stackViewHorizontalMargin:0
                                    stackViewMaxWidth:CGFLOAT_MAX];
     revampedIncognitoView.URLLoaderDelegate = self.URLLoaderDelegate;
     incognitoView = revampedIncognitoView;
   } else {
     IncognitoView* revampedIncognitoView =
         [[IncognitoView alloc] initWithFrame:CGRectZero
                showTopIncognitoImageAndTitle:NO
                    stackViewHorizontalMargin:0
                            stackViewMaxWidth:CGFLOAT_MAX];
     revampedIncognitoView.URLLoaderDelegate = self.URLLoaderDelegate;
     incognitoView = revampedIncognitoView;
   }
   incognitoView.translatesAutoresizingMaskIntoConstraints = NO;
   incognitoView.bounces = NO;

   // The Incognito view is put inside a container because it might try
   // to put constraints on its superview.
   UIView* incognitoViewContainer = [[UIView alloc] init];
   incognitoViewContainer.translatesAutoresizingMaskIntoConstraints = NO;
   [incognitoViewContainer addSubview:incognitoView];

   // A stack view is created to contain the URL label as well as the
   // Incognito view container.
   UIStackView* stackView = [[UIStackView alloc]
       initWithArrangedSubviews:@[ self.URLLabel, incognitoViewContainer ]];
   stackView.translatesAutoresizingMaskIntoConstraints = NO;
   stackView.axis = UILayoutConstraintAxisVertical;
   [self.specificContentView addSubview:stackView];

   // Create the gradient view located on the leading end of the "more" button
   // which lets the user unfold the URL label.
   UIView* gradientView = [[UIView alloc]
       initWithFrame:CGRectMake(0, 0, self.URLLabel.font.lineHeight,
                                self.URLLabel.font.lineHeight)];
   gradientView.translatesAutoresizingMaskIntoConstraints = NO;
   gradientView.backgroundColor = self.view.backgroundColor;
   CAGradientLayer* gradientLayer = [CAGradientLayer layer];
   gradientLayer.frame = gradientView.bounds;
   gradientLayer.startPoint = CGPointMake(0.0, 0.0);
   gradientLayer.endPoint = CGPointMake(1.0, 0.0);
   gradientLayer.colors =
       @[ (id)[UIColor clearColor].CGColor, (id)[UIColor whiteColor].CGColor ];
   gradientView.layer.mask = gradientLayer;
   [self.expandURLButton addSubview:gradientView];
   // Add the "more" button to the content view.
   [self.specificContentView addSubview:self.expandURLButton];

   UIBarButtonItem* cancelButton = [[UIBarButtonItem alloc]
       initWithBarButtonSystemItem:UIBarButtonSystemItemCancel
                            target:self.delegate
                            action:@selector(didTapCancelButton)];
   cancelButton.accessibilityIdentifier =
       kIncognitoInterstitialCancelButtonAccessibilityIdentifier;

   UINavigationItem* navigationRootItem =
       [[UINavigationItem alloc] initWithTitle:@""];
   navigationRootItem.rightBarButtonItem = cancelButton;

   self.navigationBar = [[UINavigationBar alloc] init];
   [self.navigationBar pushNavigationItem:navigationRootItem animated:false];
   [self updateNavigationBarAppearance];

   incognitoView.translatesAutoresizingMaskIntoConstraints = NO;
   [NSLayoutConstraint activateConstraints:@[
     [stackView.leadingAnchor
         constraintEqualToAnchor:self.specificContentView.leadingAnchor],
     [stackView.trailingAnchor
         constraintEqualToAnchor:self.specificContentView.trailingAnchor],
     [stackView.topAnchor
         constraintEqualToAnchor:self.specificContentView.topAnchor],
     [stackView.bottomAnchor
         constraintEqualToAnchor:self.specificContentView.bottomAnchor],
     [incognitoView.heightAnchor
         constraintEqualToAnchor:incognitoView.contentLayoutGuide.heightAnchor],
     [incognitoViewContainer.leadingAnchor
         constraintEqualToAnchor:incognitoView.leadingAnchor],
     [incognitoViewContainer.trailingAnchor
         constraintEqualToAnchor:incognitoView.trailingAnchor],
     [incognitoViewContainer.topAnchor
         constraintEqualToAnchor:incognitoView.topAnchor],
     [incognitoViewContainer.bottomAnchor
         constraintEqualToAnchor:incognitoView.bottomAnchor],
     [gradientView.trailingAnchor
         constraintEqualToAnchor:self.expandURLButton.leadingAnchor],
     [gradientView.bottomAnchor
         constraintEqualToAnchor:self.expandURLButton.bottomAnchor],
     [gradientView.topAnchor
         constraintEqualToAnchor:self.expandURLButton.topAnchor],
     [gradientView.widthAnchor
         constraintEqualToAnchor:gradientView.heightAnchor],
     [self.expandURLButton.trailingAnchor
         constraintEqualToAnchor:self.URLLabel.trailingAnchor],
     [self.expandURLButton.bottomAnchor
         constraintEqualToAnchor:self.URLLabel.bottomAnchor],
   ]];

   [self.view addSubview:self.navigationBar];
   self.navigationBar.translatesAutoresizingMaskIntoConstraints = NO;
   [NSLayoutConstraint activateConstraints:@[
     [self.navigationBar.leadingAnchor
         constraintEqualToAnchor:self.view.leadingAnchor],
     [self.navigationBar.trailingAnchor
         constraintEqualToAnchor:self.view.trailingAnchor],
     [self.navigationBar.topAnchor constraintEqualToAnchor:self.view.topAnchor],
   ]];
 }

 - (void)traitCollectionDidChange:(UITraitCollection*)previousTraitCollection {
   [super traitCollectionDidChange:previousTraitCollection];
   self.shouldHideBanner = IsCompactHeight(self.traitCollection);
   [self updateNavigationBarAppearance];
 }

 - (void)viewDidLayoutSubviews {
   if (self.URLIsExpanded) {
     self.expandURLButton.hidden = YES;
     self.URLLabel.numberOfLines = 0;
   } else {
     CGRect URLLabelBoundingRect = [self.URLLabel.text
         boundingRectWithSize:CGSizeMake(self.URLLabel.bounds.size.width,
                                         CGFLOAT_MAX)
                      options:NSStringDrawingUsesLineFragmentOrigin
                   attributes:@{NSFontAttributeName : self.URLLabel.font}
                      context:nil];
     int expandedNumberOfLines =
         URLLabelBoundingRect.size.height / self.URLLabel.font.lineHeight;
     self.expandURLButton.hidden =
         (expandedNumberOfLines <= kURLLabelDefaultNumberOfLines);
   }
 }

 - (void)viewDidAppear:(BOOL)animated {
   [super viewDidAppear:animated];
   // Ensure the title label is focused when the Incognito interstial appears.
   UIAccessibilityPostNotification(UIAccessibilityLayoutChangedNotification,
                                   self.titleLabel);
 }

 #pragma mark - Accessors

 - (UILabel*)URLLabel {
   if (!_URLLabel) {
     _URLLabel = [[UILabel alloc] initWithFrame:self.view.frame];
     _URLLabel.lineBreakMode = NSLineBreakByClipping;
     _URLLabel.text = self.URLText;
     _URLLabel.numberOfLines = kURLLabelDefaultNumberOfLines;
     _URLLabel.textAlignment = NSTextAlignmentCenter;
     _URLLabel.translatesAutoresizingMaskIntoConstraints = NO;
     _URLLabel.accessibilityIdentifier =
         kIncognitoInterstitialURLLabelAccessibilityIdentifier;
   }
   return _URLLabel;
 }

 - (UIButton*)expandURLButton {
   if (!_expandURLButton) {
     __weak __typeof(self) weakSelf = self;
     UIAction* readMoreAction = [UIAction actionWithHandler:^(id sender) {
       [weakSelf expandURLButtonWasTapped];
     }];

     NSAttributedString* readMoreString = [[NSAttributedString alloc]
         initWithString:l10n_util::GetNSString(
                            IDS_IOS_INCOGNITO_INTERSTITIAL_URL_READ_MORE_BUTTON)
             attributes:@{
               NSFontAttributeName : _URLLabel.font,
               NSForegroundColorAttributeName : [UIColor colorNamed:kBlueColor]
             }];

     _expandURLButton =
         [[ExtendedTouchTargetButton alloc] initWithFrame:CGRectZero
                                            primaryAction:readMoreAction];

     if (IsUIButtonConfigurationEnabled()) {
       UIButtonConfiguration* buttonConfiguration =
           [UIButtonConfiguration plainButtonConfiguration];
       buttonConfiguration.contentInsets = NSDirectionalEdgeInsetsMake(
           CGFLOAT_EPSILON, CGFLOAT_EPSILON, CGFLOAT_EPSILON, CGFLOAT_EPSILON);
       buttonConfiguration.attributedTitle = readMoreString;
       _expandURLButton.configuration = buttonConfiguration;
     } else {
       UIEdgeInsets insets = UIEdgeInsetsMake(CGFLOAT_EPSILON, CGFLOAT_EPSILON,
                                              CGFLOAT_EPSILON, CGFLOAT_EPSILON);
       SetTitleEdgeInsets(_expandURLButton, insets);
       SetContentEdgeInsets(_expandURLButton, insets);
       [_expandURLButton setAttributedTitle:readMoreString
                                   forState:UIControlStateNormal];
     }

     _expandURLButton.backgroundColor = self.view.backgroundColor;
     _expandURLButton.translatesAutoresizingMaskIntoConstraints = NO;
     // On voice over, the full info is on the URL field and this button isn't
     // needed.
     _expandURLButton.accessibilityElementsHidden = YES;
   }
   return _expandURLButton;
 }

 #pragma mark - UIScrollViewDelegate

 // This override allows scroll detection of the scroll view contained within the
 // underlying PromoStyleViewController.
 - (void)scrollViewDidScroll:(UIScrollView*)scrollView {
   // Constrain vertical content offset to positive values only.
   CGPoint contentOffset = scrollView.contentOffset;
   contentOffset.y = fmax(0, contentOffset.y);
   scrollView.contentOffset = contentOffset;

   self.scrollViewContentOffsetY = scrollView.contentOffset.y;
   [self updateNavigationBarAppearance];

   [super scrollViewDidScroll:scrollView];
 }

 #pragma mark - Private

 - (void)updateNavigationBarAppearance {
   CGFloat keyFrame0 = IsCompactHeight(self.traitCollection)
                           ? kNavigationBarFadeInCompactHeightKeyFrame0
                           : kNavigationBarFadeInKeyFrame0;
   CGFloat keyFrame1 = IsCompactHeight(self.traitCollection)
                           ? kNavigationBarFadeInCompactHeightKeyFrame1
                           : kNavigationBarFadeInKeyFrame1;
   CGFloat opacity =
       (self.scrollViewContentOffsetY - keyFrame0) / (keyFrame1 - keyFrame0);
   opacity = std::clamp(opacity, 0.0, 1.0, std::less_equal<>());

   UIColor* backgroundColor =
       [UIColor colorNamed:kGroupedPrimaryBackgroundColor];
   UIColor* shadowColor = [UIColor colorNamed:kSeparatorColor];
   CGFloat backgroundAlpha = CGColorGetAlpha(backgroundColor.CGColor);
   CGFloat shadowAlpha = CGColorGetAlpha(shadowColor.CGColor);

   if (@available(iOS 15, *)) {
     UINavigationBarAppearance* appearance =
         [[UINavigationBarAppearance alloc] init];
     [appearance configureWithOpaqueBackground];
     appearance.backgroundColor =
         [backgroundColor colorWithAlphaComponent:backgroundAlpha * opacity];
     appearance.shadowColor =
         [shadowColor colorWithAlphaComponent:shadowAlpha * opacity];

     self.navigationBar.compactAppearance = appearance;
     self.navigationBar.standardAppearance = appearance;
     self.navigationBar.scrollEdgeAppearance = appearance;
   } else {
     UIImage* whiteImage = ImageWithColor(UIColor.whiteColor);
     UIImage* navigationBarBackgroundImage = [whiteImage
         imageWithTintColor:[backgroundColor
                                colorWithAlphaComponent:backgroundAlpha *
                                                        opacity]];
     UIImage* navigationBarShadowImage = [whiteImage
         imageWithTintColor:[shadowColor
                                colorWithAlphaComponent:shadowAlpha * opacity]];
     [self.navigationBar setBackgroundImage:navigationBarBackgroundImage
                              forBarMetrics:UIBarMetricsDefault];
     self.navigationBar.shadowImage = navigationBarShadowImage;
   }

   self.navigationBar.tintColor = [UIColor colorNamed:kBlueColor];
 }

 // Called when `expandURLButton` is tapped.
 - (void)expandURLButtonWasTapped {
   self.URLIsExpanded = YES;
   [self.view setNeedsLayout];
 }

 // Set the `attributedText` attribute of `self.titleLabel` to customize the line
 // height multiple.
 - (void)fixTitleLabelLineHeightMultiple {
   NSMutableAttributedString* titleAttributedText =
       [NSAttributedStringFromUILabel(self.titleLabel) mutableCopy];
   NSMutableDictionary* attributes = [NSMutableDictionary
       dictionaryWithDictionary:[titleAttributedText attributesAtIndex:0
                                                        effectiveRange:nil]];
   NSMutableParagraphStyle* paragraphStyle =
       [[NSMutableParagraphStyle alloc] init];
   [paragraphStyle setParagraphStyle:attributes[NSParagraphStyleAttributeName]];
   paragraphStyle.lineHeightMultiple = kTitleLabelLineHeightMultiple;
   attributes[NSParagraphStyleAttributeName] = paragraphStyle;
   [titleAttributedText
       setAttributes:attributes
               range:NSMakeRange(0, titleAttributedText.length)];
   self.titleLabel.attributedText = titleAttributedText;
 }

 @end
	// Copyright 2022 The Chromium Authors
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#import "ios/chrome/browser/ui/incognito_interstitial/incognito_interstitial_view_controller.h"

	#import <algorithm>

	#import "base/apple/foundation_util.h"
	#import "base/check.h"
	#import "base/ios/ios_util.h"
	#import "ios/chrome/browser/shared/public/features/features.h"
	#import "ios/chrome/browser/shared/ui/elements/extended_touch_target_button.h"
	#import "ios/chrome/browser/shared/ui/util/attributed_string_util.h"
	#import "ios/chrome/browser/shared/ui/util/uikit_ui_util.h"
	#import "ios/chrome/browser/ui/incognito_interstitial/incognito_interstitial_constants.h"
	#import "ios/chrome/browser/ui/ntp/incognito/incognito_view.h"
	#import "ios/chrome/browser/ui/ntp/incognito/revamped_incognito_view.h"
	#import "ios/chrome/common/button_configuration_util.h"
	#import "ios/chrome/common/ui/colors/semantic_color_names.h"
	#import "ios/chrome/common/ui/util/constraints_ui_util.h"
	#import "ios/chrome/grit/ios_strings.h"
	#import "ui/base/device_form_factor.h"
	#import "ui/base/l10n/l10n_util_mac.h"

	namespace {

	// Opacity of navigation bar should be 0% at offset keyframe 0 and 100% at
	// keyframe 1.
	const CGFloat kNavigationBarFadeInKeyFrame0 = 70;
	const CGFloat kNavigationBarFadeInKeyFrame1 = 140;
	const CGFloat kNavigationBarFadeInCompactHeightKeyFrame0 = 20;
	const CGFloat kNavigationBarFadeInCompactHeightKeyFrame1 = 50;

	// Name of banner at the top of the view.
	NSString* const kIncognitoInterstitialBannerName =
	@"incognito_interstitial_screen_banner";

	// Maximum number of lines for the URL label, before the user unfolds it.
	const int kURLLabelDefaultNumberOfLines = 3;

	// Line height multiple for the title label.
	const CGFloat kTitleLabelLineHeightMultiple = 1.3;

	} // namespace

	@interface IncognitoInterstitialViewController ()

	// The navigation bar to display at the top of the view, to contain a "Cancel"
	// button.
	@property(nonatomic, strong) UINavigationBar* navigationBar;

	// Vertical offset of internal scroll view, to update navigation bar opacity.
	@property(nonatomic, assign) CGFloat scrollViewContentOffsetY;

	// Label to display the URL which is going to be opened.
	@property(nonatomic, strong) UILabel* URLLabel;

	// Button which allows the user to remove the limit on the number of lines
	// for `URLLabel`.
	@property(nonatomic, strong) UIButton* expandURLButton;

	// Whether the number of lines of `URLLabel` is unlimited.
	@property(nonatomic, assign) BOOL URLIsExpanded;

	@end

	@implementation IncognitoInterstitialViewController

	@dynamic delegate;

	#pragma mark - UIViewController

	- (void)viewDidLoad {
	self.view.accessibilityIdentifier =
	kIncognitoInterstitialAccessibilityIdentifier;

	self.bannerName = kIncognitoInterstitialBannerName;
	self.bannerSize = BannerImageSizeType::kStandard;
	self.shouldBannerFillTopSpace = YES;
	self.shouldHideBanner = IsCompactHeight(self.traitCollection);

	NSString* title =
	l10n_util::GetNSString(IDS_IOS_INCOGNITO_INTERSTITIAL_TITLE);
	self.title = title;
	self.titleText = title;
	self.titleHorizontalMargin = 0;
	self.primaryActionString = l10n_util::GetNSString(
	IDS_IOS_INCOGNITO_INTERSTITIAL_OPEN_IN_CHROME_INCOGNITO);
	self.secondaryActionString =
	l10n_util::GetNSString(IDS_IOS_INCOGNITO_INTERSTITIAL_OPEN_IN_CHROME);

	// This needs to be called after parameters of `PromoStyleViewController` have
	// been set, but before adding additional layout constraints, since these
	// constraints can only be activated once the complete view hierarchy has been
	// constructed and relevant views belong to the same hierarchy.
	[super viewDidLoad];

	// Fix the line height multiple of `self.titleLabel`.
	[self fixTitleLabelLineHeightMultiple];

	self.overrideUserInterfaceStyle = UIUserInterfaceStyleDark;
	self.modalInPresentation = YES;

	// Creating the Incognito view (same one as NTP).
	UIScrollView* incognitoView = NULL;
	if (base::FeatureList::IsEnabled(kIncognitoNtpRevamp)) {
	RevampedIncognitoView* revampedIncognitoView =
	[[RevampedIncognitoView alloc] initWithFrame:CGRectZero
	showTopIncognitoImageAndTitle:NO
	stackViewHorizontalMargin:0
	stackViewMaxWidth:CGFLOAT_MAX];
	revampedIncognitoView.URLLoaderDelegate = self.URLLoaderDelegate;
	incognitoView = revampedIncognitoView;
	} else {
	IncognitoView* revampedIncognitoView =
	[[IncognitoView alloc] initWithFrame:CGRectZero
	showTopIncognitoImageAndTitle:NO
	stackViewHorizontalMargin:0
	stackViewMaxWidth:CGFLOAT_MAX];
	revampedIncognitoView.URLLoaderDelegate = self.URLLoaderDelegate;
	incognitoView = revampedIncognitoView;
	}
	incognitoView.translatesAutoresizingMaskIntoConstraints = NO;
	incognitoView.bounces = NO;

	// The Incognito view is put inside a container because it might try
	// to put constraints on its superview.
	UIView* incognitoViewContainer = [[UIView alloc] init];
	incognitoViewContainer.translatesAutoresizingMaskIntoConstraints = NO;
	[incognitoViewContainer addSubview:incognitoView];

	// A stack view is created to contain the URL label as well as the
	// Incognito view container.
	UIStackView* stackView = [[UIStackView alloc]
	initWithArrangedSubviews:@[ self.URLLabel, incognitoViewContainer ]];
	stackView.translatesAutoresizingMaskIntoConstraints = NO;
	stackView.axis = UILayoutConstraintAxisVertical;
	[self.specificContentView addSubview:stackView];

	// Create the gradient view located on the leading end of the "more" button
	// which lets the user unfold the URL label.
	UIView* gradientView = [[UIView alloc]
	initWithFrame:CGRectMake(0, 0, self.URLLabel.font.lineHeight,
	self.URLLabel.font.lineHeight)];
	gradientView.translatesAutoresizingMaskIntoConstraints = NO;
	gradientView.backgroundColor = self.view.backgroundColor;
	CAGradientLayer* gradientLayer = [CAGradientLayer layer];
	gradientLayer.frame = gradientView.bounds;
	gradientLayer.startPoint = CGPointMake(0.0, 0.0);
	gradientLayer.endPoint = CGPointMake(1.0, 0.0);
	gradientLayer.colors =
	@[ (id)[UIColor clearColor].CGColor, (id)[UIColor whiteColor].CGColor ];
	gradientView.layer.mask = gradientLayer;
	[self.expandURLButton addSubview:gradientView];
	// Add the "more" button to the content view.
	[self.specificContentView addSubview:self.expandURLButton];

	UIBarButtonItem* cancelButton = [[UIBarButtonItem alloc]
	initWithBarButtonSystemItem:UIBarButtonSystemItemCancel
	target:self.delegate
	action:@selector(didTapCancelButton)];
	cancelButton.accessibilityIdentifier =
	kIncognitoInterstitialCancelButtonAccessibilityIdentifier;

	UINavigationItem* navigationRootItem =
	[[UINavigationItem alloc] initWithTitle:@""];
	navigationRootItem.rightBarButtonItem = cancelButton;

	self.navigationBar = [[UINavigationBar alloc] init];
	[self.navigationBar pushNavigationItem:navigationRootItem animated:false];
	[self updateNavigationBarAppearance];

	incognitoView.translatesAutoresizingMaskIntoConstraints = NO;
	[NSLayoutConstraint activateConstraints:@[
	[stackView.leadingAnchor
	constraintEqualToAnchor:self.specificContentView.leadingAnchor],
	[stackView.trailingAnchor
	constraintEqualToAnchor:self.specificContentView.trailingAnchor],
	[stackView.topAnchor
	constraintEqualToAnchor:self.specificContentView.topAnchor],
	[stackView.bottomAnchor
	constraintEqualToAnchor:self.specificContentView.bottomAnchor],
	[incognitoView.heightAnchor
	constraintEqualToAnchor:incognitoView.contentLayoutGuide.heightAnchor],
	[incognitoViewContainer.leadingAnchor
	constraintEqualToAnchor:incognitoView.leadingAnchor],
	[incognitoViewContainer.trailingAnchor
	constraintEqualToAnchor:incognitoView.trailingAnchor],
	[incognitoViewContainer.topAnchor
	constraintEqualToAnchor:incognitoView.topAnchor],
	[incognitoViewContainer.bottomAnchor
	constraintEqualToAnchor:incognitoView.bottomAnchor],
	[gradientView.trailingAnchor
	constraintEqualToAnchor:self.expandURLButton.leadingAnchor],
	[gradientView.bottomAnchor
	constraintEqualToAnchor:self.expandURLButton.bottomAnchor],
	[gradientView.topAnchor
	constraintEqualToAnchor:self.expandURLButton.topAnchor],
	[gradientView.widthAnchor
	constraintEqualToAnchor:gradientView.heightAnchor],
	[self.expandURLButton.trailingAnchor
	constraintEqualToAnchor:self.URLLabel.trailingAnchor],
	[self.expandURLButton.bottomAnchor
	constraintEqualToAnchor:self.URLLabel.bottomAnchor],
	]];

	[self.view addSubview:self.navigationBar];
	self.navigationBar.translatesAutoresizingMaskIntoConstraints = NO;
	[NSLayoutConstraint activateConstraints:@[
	[self.navigationBar.leadingAnchor
	constraintEqualToAnchor:self.view.leadingAnchor],
	[self.navigationBar.trailingAnchor
	constraintEqualToAnchor:self.view.trailingAnchor],
	[self.navigationBar.topAnchor constraintEqualToAnchor:self.view.topAnchor],
	]];
	}

	- (void)traitCollectionDidChange:(UITraitCollection*)previousTraitCollection {
	[super traitCollectionDidChange:previousTraitCollection];
	self.shouldHideBanner = IsCompactHeight(self.traitCollection);
	[self updateNavigationBarAppearance];
	}

	- (void)viewDidLayoutSubviews {
	if (self.URLIsExpanded) {
	self.expandURLButton.hidden = YES;
	self.URLLabel.numberOfLines = 0;
	} else {
	CGRect URLLabelBoundingRect = [self.URLLabel.text
	boundingRectWithSize:CGSizeMake(self.URLLabel.bounds.size.width,
	CGFLOAT_MAX)
	options:NSStringDrawingUsesLineFragmentOrigin
	attributes:@{NSFontAttributeName : self.URLLabel.font}
	context:nil];
	int expandedNumberOfLines =
	URLLabelBoundingRect.size.height / self.URLLabel.font.lineHeight;
	self.expandURLButton.hidden =
	(expandedNumberOfLines <= kURLLabelDefaultNumberOfLines);
	}
	}

	- (void)viewDidAppear:(BOOL)animated {
	[super viewDidAppear:animated];
	// Ensure the title label is focused when the Incognito interstial appears.
	UIAccessibilityPostNotification(UIAccessibilityLayoutChangedNotification,
	self.titleLabel);
	}

	#pragma mark - Accessors

	- (UILabel*)URLLabel {
	if (!_URLLabel) {
	_URLLabel = [[UILabel alloc] initWithFrame:self.view.frame];
	_URLLabel.lineBreakMode = NSLineBreakByClipping;
	_URLLabel.text = self.URLText;
	_URLLabel.numberOfLines = kURLLabelDefaultNumberOfLines;
	_URLLabel.textAlignment = NSTextAlignmentCenter;
	_URLLabel.translatesAutoresizingMaskIntoConstraints = NO;
	_URLLabel.accessibilityIdentifier =
	kIncognitoInterstitialURLLabelAccessibilityIdentifier;
	}
	return _URLLabel;
	}

	- (UIButton*)expandURLButton {
	if (!_expandURLButton) {
	__weak __typeof(self) weakSelf = self;
	UIAction* readMoreAction = [UIAction actionWithHandler:^(id sender) {
	[weakSelf expandURLButtonWasTapped];
	}];

	NSAttributedString* readMoreString = [[NSAttributedString alloc]
	initWithString:l10n_util::GetNSString(
	IDS_IOS_INCOGNITO_INTERSTITIAL_URL_READ_MORE_BUTTON)
	attributes:@{
	NSFontAttributeName : _URLLabel.font,
	NSForegroundColorAttributeName : [UIColor colorNamed:kBlueColor]
	}];

	_expandURLButton =
	[[ExtendedTouchTargetButton alloc] initWithFrame:CGRectZero
	primaryAction:readMoreAction];

	if (IsUIButtonConfigurationEnabled()) {
	UIButtonConfiguration* buttonConfiguration =
	[UIButtonConfiguration plainButtonConfiguration];
	buttonConfiguration.contentInsets = NSDirectionalEdgeInsetsMake(
	CGFLOAT_EPSILON, CGFLOAT_EPSILON, CGFLOAT_EPSILON, CGFLOAT_EPSILON);
	buttonConfiguration.attributedTitle = readMoreString;
	_expandURLButton.configuration = buttonConfiguration;
	} else {
	UIEdgeInsets insets = UIEdgeInsetsMake(CGFLOAT_EPSILON, CGFLOAT_EPSILON,
	CGFLOAT_EPSILON, CGFLOAT_EPSILON);
	SetTitleEdgeInsets(_expandURLButton, insets);
	SetContentEdgeInsets(_expandURLButton, insets);
	[_expandURLButton setAttributedTitle:readMoreString
	forState:UIControlStateNormal];
	}

	_expandURLButton.backgroundColor = self.view.backgroundColor;
	_expandURLButton.translatesAutoresizingMaskIntoConstraints = NO;
	// On voice over, the full info is on the URL field and this button isn't
	// needed.
	_expandURLButton.accessibilityElementsHidden = YES;
	}
	return _expandURLButton;
	}

	#pragma mark - UIScrollViewDelegate

	// This override allows scroll detection of the scroll view contained within the
	// underlying PromoStyleViewController.
	- (void)scrollViewDidScroll:(UIScrollView*)scrollView {
	// Constrain vertical content offset to positive values only.
	CGPoint contentOffset = scrollView.contentOffset;
	contentOffset.y = fmax(0, contentOffset.y);
	scrollView.contentOffset = contentOffset;

	self.scrollViewContentOffsetY = scrollView.contentOffset.y;
	[self updateNavigationBarAppearance];

	[super scrollViewDidScroll:scrollView];
	}

	#pragma mark - Private

	- (void)updateNavigationBarAppearance {
	CGFloat keyFrame0 = IsCompactHeight(self.traitCollection)
	? kNavigationBarFadeInCompactHeightKeyFrame0
	: kNavigationBarFadeInKeyFrame0;
	CGFloat keyFrame1 = IsCompactHeight(self.traitCollection)
	? kNavigationBarFadeInCompactHeightKeyFrame1
	: kNavigationBarFadeInKeyFrame1;
	CGFloat opacity =
	(self.scrollViewContentOffsetY - keyFrame0) / (keyFrame1 - keyFrame0);
	opacity = std::clamp(opacity, 0.0, 1.0, std::less_equal<>());

	UIColor* backgroundColor =
	[UIColor colorNamed:kGroupedPrimaryBackgroundColor];
	UIColor* shadowColor = [UIColor colorNamed:kSeparatorColor];
	CGFloat backgroundAlpha = CGColorGetAlpha(backgroundColor.CGColor);
	CGFloat shadowAlpha = CGColorGetAlpha(shadowColor.CGColor);

	if (@available(iOS 15, *)) {
	UINavigationBarAppearance* appearance =
	[[UINavigationBarAppearance alloc] init];
	[appearance configureWithOpaqueBackground];
	appearance.backgroundColor =
	[backgroundColor colorWithAlphaComponent:backgroundAlpha * opacity];
	appearance.shadowColor =
	[shadowColor colorWithAlphaComponent:shadowAlpha * opacity];

	self.navigationBar.compactAppearance = appearance;
	self.navigationBar.standardAppearance = appearance;
	self.navigationBar.scrollEdgeAppearance = appearance;
	} else {
	UIImage* whiteImage = ImageWithColor(UIColor.whiteColor);
	UIImage* navigationBarBackgroundImage = [whiteImage
	imageWithTintColor:[backgroundColor
	colorWithAlphaComponent:backgroundAlpha *
	opacity]];
	UIImage* navigationBarShadowImage = [whiteImage
	imageWithTintColor:[shadowColor
	colorWithAlphaComponent:shadowAlpha * opacity]];
	[self.navigationBar setBackgroundImage:navigationBarBackgroundImage
	forBarMetrics:UIBarMetricsDefault];
	self.navigationBar.shadowImage = navigationBarShadowImage;
	}

	self.navigationBar.tintColor = [UIColor colorNamed:kBlueColor];
	}

	// Called when `expandURLButton` is tapped.
	- (void)expandURLButtonWasTapped {
	self.URLIsExpanded = YES;
	[self.view setNeedsLayout];
	}

	// Set the `attributedText` attribute of `self.titleLabel` to customize the line
	// height multiple.
	- (void)fixTitleLabelLineHeightMultiple {
	NSMutableAttributedString* titleAttributedText =
	[NSAttributedStringFromUILabel(self.titleLabel) mutableCopy];
	NSMutableDictionary* attributes = [NSMutableDictionary
	dictionaryWithDictionary:[titleAttributedText attributesAtIndex:0
	effectiveRange:nil]];
	NSMutableParagraphStyle* paragraphStyle =
	[[NSMutableParagraphStyle alloc] init];
	[paragraphStyle setParagraphStyle:attributes[NSParagraphStyleAttributeName]];
	paragraphStyle.lineHeightMultiple = kTitleLabelLineHeightMultiple;
	attributes[NSParagraphStyleAttributeName] = paragraphStyle;
	[titleAttributedText
	setAttributes:attributes
	range:NSMakeRange(0, titleAttributedText.length)];
	self.titleLabel.attributedText = titleAttributedText;
	}

	@end