How to Bridge Native iOS Code to React Native

// Custom annotation toolbar subclass that adds a Clear button that removes all visible annotations.
@interface CustomButtonAnnotationToolbar : PSPDFAnnotationToolbar

@property (nonatomic) PSPDFToolbarButton *clearAnnotationsButton;

@end

@implementation CustomButtonAnnotationToolbar

#pragma mark - Lifecycle

- (instancetype)initWithAnnotationStateManager:(PSPDFAnnotationStateManager *)annotationStateManager {
  if ((self = [super initWithAnnotationStateManager:annotationStateManager])) {
    // The biggest challenge here isn't the Clear button, but rather correctly updating the Clear button's states.
    NSNotificationCenter *dnc = NSNotificationCenter.defaultCenter;
    [dnc addObserver:self selector:@selector(annotationChangedNotification:) name:PSPDFAnnotationChangedNotification object:nil];
    [dnc addObserver:self selector:@selector(annotationChangedNotification:) name:PSPDFAnnotationsAddedNotification object:nil];
    [dnc addObserver:self selector:@selector(annotationChangedNotification:) name:PSPDFAnnotationsRemovedNotification object:nil];

    // We could also use the delegate, but this is cleaner.
    [dnc addObserver:self selector:@selector(willShowSpreadViewNotification:) name:PSPDFDocumentViewControllerWillBeginDisplayingSpreadViewNotification object:nil];

    // Add Clear button.
    UIImage *clearImage = [[PSPDFKitGlobal imageNamed:@"trash"] imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];
    _clearAnnotationsButton = [PSPDFToolbarButton new];
    _clearAnnotationsButton.accessibilityLabel = @"Clear";
    [_clearAnnotationsButton setImage:clearImage];
    [_clearAnnotationsButton addTarget:self action:@selector(clearButtonPressed:) forControlEvents:UIControlEventTouchUpInside];

    [self updateClearAnnotationButton];
    self.additionalButtons = @[_clearAnnotationsButton];

    // Hide the callout and the signature buttons from the annotation toolbar.
    NSMutableArray <PSPDFAnnotationToolbarConfiguration *> *toolbarConfigurations = [NSMutableArray<PSPDFAnnotationToolbarConfiguration *> new];;
    for(PSPDFAnnotationToolbarConfiguration *toolbarConfiguration in self.configurations) {
      NSMutableArray<PSPDFAnnotationGroup *> *filteredGroups = [NSMutableArray<PSPDFAnnotationGroup *> new];
      for (PSPDFAnnotationGroup *group in toolbarConfiguration.annotationGroups) {
        NSMutableArray<PSPDFAnnotationGroupItem *> *filteredItems = [NSMutableArray<PSPDFAnnotationGroupItem *> new];
        for(PSPDFAnnotationGroupItem *item in group.items) {
          BOOL isCallout = [item.variant isEqualToString:PSPDFAnnotationVariantStringFreeTextCallout];
          BOOL isSignature = [item.type isEqualToString:PSPDFAnnotationStringSignature];
          if (!isCallout && !isSignature) {
            [filteredItems addObject:item];
          }
        }
        if (filteredItems.count) {
          [filteredGroups addObject:[PSPDFAnnotationGroup groupWithItems:filteredItems]];
        }
      }
      [toolbarConfigurations addObject:[[PSPDFAnnotationToolbarConfiguration alloc] initWithAnnotationGroups:filteredGroups]];
    }

    self.configurations = [toolbarConfigurations copy];
  }
  return self;
}

- (void)dealloc {
  [NSNotificationCenter.defaultCenter removeObserver:self];
}

///////////////////////////////////////////////////////////////////////////////////////////
#pragma mark - Clear Button Action

- (void)clearButtonPressed:(id)sender {
  // Iterate over all visible pages and remove everything but links and widgets (forms).
  PSPDFViewController *pdfController = self.annotationStateManager.pdfController;
  PSPDFDocument *document = pdfController.document;
  for (PSPDFPageView *pageView in pdfController.visiblePageViews) {
    NSArray<PSPDFAnnotation *> *annotations = [document annotationsForPageAtIndex:pageView.pageIndex type:PSPDFAnnotationTypeAll & ~(PSPDFAnnotationTypeLink | PSPDFAnnotationTypeWidget)];
    [document removeAnnotations:annotations options:nil];

    // Remove any annotation on the page as well (updates views).
    // Alternatively, you can call `reloadData` on the `pdfController` as well.
    for (PSPDFAnnotation *annotation in annotations) {
      [pageView removeAnnotation:annotation options:nil animated:YES];
    }
  }
}

///////////////////////////////////////////////////////////////////////////////////////////
#pragma mark - Notifications

// If we detect annotation changes, schedule a reload.
- (void)annotationChangedNotification:(NSNotification *)notification {
  // Reevaluate toolbar button.
  if (self.window) {
    [self updateClearAnnotationButton];
  }
}

- (void)willShowSpreadViewNotification:(NSNotification *)notification {
  [self updateClearAnnotationButton];
}

///////////////////////////////////////////////////////////////////////////////////////////
#pragma mark - PSPDFAnnotationStateManagerDelegate

- (void)annotationStateManager:(PSPDFAnnotationStateManager *)manager didChangeUndoState:(BOOL)undoEnabled redoState:(BOOL)redoEnabled {
  [super annotationStateManager:manager didChangeUndoState:undoEnabled redoState:redoEnabled];
  [self updateClearAnnotationButton];
}

///////////////////////////////////////////////////////////////////////////////////////////
#pragma mark - Private

- (void)updateClearAnnotationButton {
  __block BOOL annotationsFound = NO;
  PSPDFViewController *pdfController = self.annotationStateManager.pdfController;
  [pdfController.visiblePageIndexes enumerateIndexesUsingBlock:^(NSUInteger pageIndex, BOOL *stop) {
    NSArray<PSPDFAnnotation *> *annotations = [pdfController.document annotationsForPageAtIndex:pageIndex type:PSPDFAnnotationTypeAll & ~(PSPDFAnnotationTypeLink | PSPDFAnnotationTypeWidget)];
    if (annotations.count > 0) {
      annotationsFound = YES;
      *stop = YES;
    }
  }];
  self.clearAnnotationsButton.enabled = annotationsFound;
}

@end

— (instancetype)initWithFrame:(CGRect)frame {
  if ((self = [super initWithFrame:frame])) {
    // Set configuration to use the custom annotation toolbar when initializing the `PSPDFViewController`.
    // For more details, see our documentation: https://pspdfkit.com/guides/ios/customizing-the-interface/customize-the-annotation-toolbar/
-    _pdfController = [[RCTPSPDFKitViewController alloc] init];
+    _pdfController = [[PSPDFViewController alloc] initWithDocument:nil configuration:[PSPDFConfiguration
+    configurationWithBuilder:^(PSPDFConfigurationBuilder *builder) {
+     [builder overrideClass:PSPDFAnnotationToolbar.class withClass:CustomButtonAnnotationToolbar.class];
+    }]];

    // Store the `closeButton`'s target and selector in order to call it later.
    _closeButtonAttributes = @{@"target" : _pdfController.closeButtonItem.target,
                              @"action" : NSStringFromSelector(_pdfController.closeButtonItem.action)};

    [_pdfController.closeButtonItem setTarget:self];
    [_pdfController.closeButtonItem setAction:@selector(closeButtonPressed:)];
    _closeButton = _pdfController.closeButtonItem;

    [NSNotificationCenter.defaultCenter addObserver:self selector:@selector(annotationChangedNotification:) name:PSPDFAnnotationChangedNotification object:nil];
    [NSNotificationCenter.defaultCenter addObserver:self selector:@selector(annotationChangedNotification:) name:PSPDFAnnotationsAddedNotification object:nil];
    [NSNotificationCenter.defaultCenter addObserver:self selector:@selector(annotationChangedNotification:) name:PSPDFAnnotationsRemovedNotification object:nil];

    [NSNotificationCenter.defaultCenter addObserver:self selector:@selector(spreadIndexDidChange:) name:PSPDFDocumentViewControllerSpreadIndexDidChangeNotification object:nil];
  }

  return self;
}