feat: cleanup the code, split into smaller functions (#1014)

okwasniewski · web-flow · commit 4b648037fae3 · 2025-07-31T17:58:05.000+02:00
diff --git a/ios/RNCPagerViewComponentView.mm b/ios/RNCPagerViewComponentView.mm
@@ -176,24 +176,9 @@ - (void)updateProps:(const facebook::react::Props::Shared &)props oldProps:(cons
     [super updateProps:props oldProps:oldProps];
 }
 
-- (void)handleCommand:(const NSString *)commandName args:(const NSArray *)args {
-   RCTRNCViewPagerHandleCommand(self, commandName, args);
-}
 
 #pragma mark - Internal methods
 
-- (void)setPage:(NSInteger)index {
-    [self goTo:index animated:YES];
-}
-
-- (void)setPageWithoutAnimation:(NSInteger)index {
-    [self goTo:index animated:NO];
-}
-
-- (void)setScrollEnabledImperatively:(BOOL)scrollEnabled {
-    [scrollView setScrollEnabled:scrollEnabled];
-}
-
 - (void)disableSwipe {
     self.nativePageViewController.view.userInteractionEnabled = NO;
 }
@@ -244,9 +229,9 @@ - (void)setPagerViewControllers:(NSInteger)index
         __strong RNCPagerViewComponentView *strongSelf = weakSelf;
         [strongSelf enableSwipe];
         if (strongSelf->_eventEmitter != nullptr ) {
-            const auto strongEventEmitter = *std::dynamic_pointer_cast<const RNCViewPagerEventEmitter>(strongSelf->_eventEmitter);
+            const auto eventEmitter = [strongSelf pagerEventEmitter];
             int position = (int) index;
-            strongEventEmitter.onPageSelected(RNCViewPagerEventEmitter::OnPageSelected{.position =  static_cast<double>(position)});
+            eventEmitter->onPageSelected(RNCViewPagerEventEmitter::OnPageSelected{.position =  static_cast<double>(position)});
             strongSelf->_currentIndex = index;
         }
         [strongSelf updateLayoutMetrics:strongSelf->_layoutMetrics oldLayoutMetrics:strongSelf->_oldLayoutMetrics];
@@ -279,14 +264,14 @@ - (UIViewController *)currentlyDisplayed {
 #pragma mark - UIScrollViewDelegate
 
 - (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
-    const auto strongEventEmitter = *std::dynamic_pointer_cast<const RNCViewPagerEventEmitter>(_eventEmitter);
-    strongEventEmitter.onPageScrollStateChanged(RNCViewPagerEventEmitter::OnPageScrollStateChanged{.pageScrollState =  RNCViewPagerEventEmitter::OnPageScrollStateChangedPageScrollState::Dragging });
+    const auto eventEmitter = [self pagerEventEmitter];
+    eventEmitter->onPageScrollStateChanged(RNCViewPagerEventEmitter::OnPageScrollStateChanged{.pageScrollState =  RNCViewPagerEventEmitter::OnPageScrollStateChangedPageScrollState::Dragging });
 }
 
 - (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset {
     
-    const auto strongEventEmitter = *std::dynamic_pointer_cast<const RNCViewPagerEventEmitter>(_eventEmitter);
-    strongEventEmitter.onPageScrollStateChanged(RNCViewPagerEventEmitter::OnPageScrollStateChanged{.pageScrollState =  RNCViewPagerEventEmitter::OnPageScrollStateChangedPageScrollState::Settling });
+    const auto eventEmitter = [self pagerEventEmitter];
+    eventEmitter->onPageScrollStateChanged(RNCViewPagerEventEmitter::OnPageScrollStateChanged{.pageScrollState =  RNCViewPagerEventEmitter::OnPageScrollStateChangedPageScrollState::Settling });
     
     if (!_overdrag) {
         NSInteger maxIndex = _nativeChildrenViewControllers.count - 1;
@@ -299,44 +284,26 @@ - (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoi
             CGPoint croppedOffset = [self isHorizontal] ? CGPointMake(topBound, 0) : CGPointMake(0, topBound);
             *targetContentOffset = croppedOffset;
             
-            strongEventEmitter.onPageScrollStateChanged(RNCViewPagerEventEmitter::OnPageScrollStateChanged{.pageScrollState =  RNCViewPagerEventEmitter::OnPageScrollStateChangedPageScrollState::Idle });
+            eventEmitter->onPageScrollStateChanged(RNCViewPagerEventEmitter::OnPageScrollStateChanged{.pageScrollState =  RNCViewPagerEventEmitter::OnPageScrollStateChangedPageScrollState::Idle });
         }
     }
-    
-   
 }
 
 - (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
-    const auto strongEventEmitter = *std::dynamic_pointer_cast<const RNCViewPagerEventEmitter>(_eventEmitter);
-    strongEventEmitter.onPageScrollStateChanged(RNCViewPagerEventEmitter::OnPageScrollStateChanged{.pageScrollState =  RNCViewPagerEventEmitter::OnPageScrollStateChangedPageScrollState::Idle });
-}
-
-- (BOOL)isHorizontalRtlLayout {
-    return self.isHorizontal && !self.isLtrLayout;
-}
-
-- (BOOL)isHorizontal {
-    return _nativePageViewController.navigationOrientation == UIPageViewControllerNavigationOrientationHorizontal;
+    const auto eventEmitter = [self pagerEventEmitter];
+    eventEmitter->onPageScrollStateChanged(RNCViewPagerEventEmitter::OnPageScrollStateChanged{.pageScrollState =  RNCViewPagerEventEmitter::OnPageScrollStateChangedPageScrollState::Idle });
 }
 
-- (BOOL)isLtrLayout {
-    return [_layoutDirection isEqualToString: @"ltr"];
-}
 
 - (void)scrollViewDidScroll:(UIScrollView *)scrollView {
-    CGPoint point = scrollView.contentOffset;
-    
-    float offset = 0;
-    
-    if (self.isHorizontal) {
-        if (scrollView.frame.size.width != 0) {
-            offset = (point.x - scrollView.frame.size.width)/scrollView.frame.size.width;
-        }
-    } else {
-        if (scrollView.frame.size.height != 0) {
-            offset = (point.y - scrollView.frame.size.height)/scrollView.frame.size.height;
-        }
+    CGFloat contentOffset = [self isHorizontal] ? scrollView.contentOffset.x : scrollView.contentOffset.y;
+    CGFloat frameSize = [self isHorizontal] ? scrollView.frame.size.width : scrollView.frame.size.height;
+  
+    if (frameSize == 0) {
+        return;
     }
+
+    float offset = (contentOffset - frameSize)/frameSize;
     
     float absoluteOffset = fabs(offset);
     
@@ -372,21 +339,10 @@ - (void)scrollViewDidScroll:(UIScrollView *)scrollView {
     }
     
     float interpolatedOffset = absoluteOffset * labs(_destinationIndex - _currentIndex);
-    
-    const auto strongEventEmitter = *std::dynamic_pointer_cast<const RNCViewPagerEventEmitter>(_eventEmitter);
-    int eventPosition = (int) position;
-    strongEventEmitter.onPageScroll(RNCViewPagerEventEmitter::OnPageScroll{.position =  static_cast<double>(eventPosition), .offset = interpolatedOffset});
-
-    // This is temporary workaround to allow animations based on onPageScroll event
-    // until Fabric implements proper NativeAnimationDriver,
-    // see: https://github.com/facebook/react-native/blob/44f431b471c243c92284aa042d3807ba4d04af65/packages/react-native/React/Fabric/Mounting/ComponentViews/ScrollView/RCTScrollViewComponentView.mm#L59
-    NSDictionary *userInfo = [NSDictionary dictionaryWithObjectsAndKeys:[[RCTOnPageScrollEvent alloc] initWithReactTag:[NSNumber numberWithInt:self.tag] position:@(position) offset:@(interpolatedOffset)], @"event", nil];
-    [[NSNotificationCenter defaultCenter] postNotificationName:@"RCTNotifyEventDispatcherObserversOfEvent_DEPRECATED"
-                                                        object:nil
-                                                      userInfo:userInfo];
+  
+    [self sendScrollEventsForPosition:position offset:interpolatedOffset];
 }
 
-
 #pragma mark - UIPageViewControllerDelegate
 
 - (void)pageViewController:(UIPageViewController *)pageViewController
@@ -398,9 +354,9 @@ - (void)pageViewController:(UIPageViewController *)pageViewController
         NSUInteger currentIndex = [_nativeChildrenViewControllers indexOfObject:currentVC];
         _currentIndex = currentIndex;
         int position = (int) currentIndex;
-        const auto strongEventEmitter = *std::dynamic_pointer_cast<const RNCViewPagerEventEmitter>(_eventEmitter);
-        strongEventEmitter.onPageSelected(RNCViewPagerEventEmitter::OnPageSelected{.position =  static_cast<double>(position)});
-        strongEventEmitter.onPageScroll(RNCViewPagerEventEmitter::OnPageScroll{.position =  static_cast<double>(position), .offset =  0.0});
+        const auto eventEmitter = [self pagerEventEmitter];
+        eventEmitter->onPageSelected(RNCViewPagerEventEmitter::OnPageSelected{.position =  static_cast<double>(position)});
+        eventEmitter->onPageScroll(RNCViewPagerEventEmitter::OnPageScroll{.position =  static_cast<double>(position), .offset =  0.0});
     }
 }
 
@@ -419,6 +375,67 @@ - (UIViewController *)pageViewController:(UIPageViewController *)pageViewControl
     return [self nextControllerForController:viewController inDirection:direction];
 }
 
+#pragma mark - Imperative methods exposed to React Native
+
+- (void)handleCommand:(const NSString *)commandName args:(const NSArray *)args {
+   RCTRNCViewPagerHandleCommand(self, commandName, args);
+}
+
+- (void)setPage:(NSInteger)index {
+    [self goTo:index animated:YES];
+}
+
+- (void)setPageWithoutAnimation:(NSInteger)index {
+    [self goTo:index animated:NO];
+}
+
+- (void)setScrollEnabledImperatively:(BOOL)scrollEnabled {
+    [scrollView setScrollEnabled:scrollEnabled];
+}
+
+#pragma mark - Helpers
+
+- (BOOL)isHorizontalRtlLayout {
+    return self.isHorizontal && !self.isLtrLayout;
+}
+
+- (BOOL)isHorizontal {
+    return _nativePageViewController.navigationOrientation == UIPageViewControllerNavigationOrientationHorizontal;
+}
+
+- (BOOL)isLtrLayout {
+    return [_layoutDirection isEqualToString: @"ltr"];
+}
+
+- (std::shared_ptr<const RNCViewPagerEventEmitter>)pagerEventEmitter
+{
+  if (!_eventEmitter) {
+    return nullptr;
+  }
+
+  assert(std::dynamic_pointer_cast<const RNCViewPagerEventEmitter>(_eventEmitter));
+  return std::static_pointer_cast<const RNCViewPagerEventEmitter>(_eventEmitter);
+}
+
+- (void)sendScrollEventsForPosition:(NSInteger)position offset:(CGFloat)offset {
+    const auto eventEmitter = [self pagerEventEmitter];
+    eventEmitter->onPageScroll(RNCViewPagerEventEmitter::OnPageScroll{
+        .position = static_cast<double>(position),
+        .offset = offset
+    });
+  
+    // This is temporary workaround to allow animations based on onPageScroll event
+    // until Fabric implements proper NativeAnimationDriver,
+    // see: https://github.com/facebook/react-native/blob/44f431b471c243c92284aa042d3807ba4d04af65/packages/react-native/React/Fabric/Mounting/ComponentViews/ScrollView/RCTScrollViewComponentView.mm#L59
+    RCTOnPageScrollEvent *event = [[RCTOnPageScrollEvent alloc] initWithReactTag:@(self.tag)
+                                                                        position:@(position)
+                                                                          offset:@(offset)];
+    NSDictionary *userInfo = @{@"event": event};
+    [[NSNotificationCenter defaultCenter] postNotificationName:@"RCTNotifyEventDispatcherObserversOfEvent_DEPRECATED"
+                                                        object:nil
+                                                      userInfo:userInfo];
+}
+
 #pragma mark - RCTComponentViewProtocol
 
 + (ComponentDescriptorProvider)componentDescriptorProvider
