Fixed broken listview header alignment

React/Base/RCTConvert.h

@@ -39,6 +39,7 @@
 + (NSString *)NSString:(id)json;
 + (NSNumber *)NSNumber:(id)json;
 + (NSData *)NSData:(id)json;
++ (NSIndexSet *)NSIndexSet:(id)json;
 
 + (NSURL *)NSURL:(id)json;
 + (NSURLRequest *)NSURLRequest:(id)json;

React/Base/RCTConvert.m

@@ -64,6 +64,20 @@ RCT_CONVERTER(NSString *, NSString, description)
   return [[self NSString:json] dataUsingEncoding:NSUTF8StringEncoding];
 }
 
++ (NSIndexSet *)NSIndexSet:(id)json
+{
+  json = [self NSNumberArray:json];
+  NSMutableIndexSet *indexSet = [[NSMutableIndexSet alloc] init];
+  for (NSNumber *number in json) {
+    NSInteger index = number.integerValue;
+    if (RCT_DEBUG && index < 0) {
+      RCTLogError(@"Invalid index value %zd. Indices must be positive.", index);
+    }
+    [indexSet addIndex:index];
+  }
+  return indexSet;
+}
+
 + (NSURL *)NSURL:(id)json
 {
   NSString *path = [self NSString:json];

React/Base/RCTDevMenu.m

@@ -119,8 +119,6 @@ RCT_EXPORT_MODULE()
 
 - (void)updateSettings
 {
-  _settings = [NSMutableDictionary dictionaryWithDictionary:[_defaults objectForKey:RCTDevMenuSettingsKey]];
-
   __weak RCTDevMenu *weakSelf = self;
   dispatch_async(dispatch_get_main_queue(), ^{
     RCTDevMenu *strongSelf = weakSelf;
@@ -128,6 +126,8 @@ RCT_EXPORT_MODULE()
       return;
     }
 
+    strongSelf->_settings = [NSMutableDictionary dictionaryWithDictionary:[strongSelf->_defaults objectForKey:RCTDevMenuSettingsKey]];
+
     strongSelf.shakeToShow = [strongSelf->_settings[@"shakeToShow"] ?: @YES boolValue];
     strongSelf.profilingEnabled = [strongSelf->_settings[@"profilingEnabled"] ?: @NO boolValue];
     strongSelf.liveReloadEnabled = [strongSelf->_settings[@"liveReloadEnabled"] ?: @NO boolValue];

React/Views/RCTScrollView.h

@@ -45,6 +45,6 @@
 @property (nonatomic, assign) BOOL automaticallyAdjustContentInsets;
 @property (nonatomic, assign) NSTimeInterval scrollEventThrottle;
 @property (nonatomic, assign) BOOL centerContent;
-@property (nonatomic, copy) NSArray *stickyHeaderIndices;
+@property (nonatomic, copy) NSIndexSet *stickyHeaderIndices;
 
 @end

React/Views/RCTScrollView.m

@@ -28,8 +28,8 @@ CGFloat const ZINDEX_STICKY_HEADER = 50;
  */
 @interface RCTCustomScrollView : UIScrollView<UIGestureRecognizerDelegate>
 
-@property (nonatomic, copy, readwrite) NSArray *stickyHeaderIndices;
-@property (nonatomic, readwrite, assign) BOOL centerContent;
+@property (nonatomic, copy) NSIndexSet *stickyHeaderIndices;
+@property (nonatomic, assign) BOOL centerContent;
 
 @end
 
@@ -155,97 +155,72 @@ CGFloat const ZINDEX_STICKY_HEADER = 50;
   [super setContentOffset:contentOffset];
 }
 
-- (void)setBounds:(CGRect)bounds
-{
-  [super setBounds:bounds];
-  [self dockClosestSectionHeader];
-}
-
 - (void)dockClosestSectionHeader
 {
   UIView *contentView = [self contentView];
-  if (_stickyHeaderIndices.count == 0 || !contentView) {
+  CGFloat scrollTop = self.bounds.origin.y + self.contentInset.top;
+
+  // Find the section headers that need to be docked
+  __block UIView *previousHeader = nil;
+  __block UIView *currentHeader = nil;
+  __block UIView *nextHeader = nil;
+  NSInteger subviewCount = contentView.reactSubviews.count;
+  [_stickyHeaderIndices enumerateIndexesWithOptions:0 usingBlock:^(NSUInteger idx, BOOL *stop) {
+
+    if (idx >= subviewCount) {
+      RCTLogError(@"Sticky header index %zd was outside the range {0, %zd}", idx, subviewCount);
+      return;
+    }
+
+    UIView *header = contentView.reactSubviews[idx];
+
+    // If nextHeader not yet found, search for docked headers
+    if (!nextHeader) {
+      CGFloat height = header.bounds.size.height;
+      CGFloat top = header.center.y - height * header.layer.anchorPoint.y;
+      if (top > scrollTop) {
+        nextHeader = header;
+      } else {
+        previousHeader = currentHeader;
+        currentHeader = header;
+      }
+    }
+
+    // Reset transforms for header views
+    header.transform = CGAffineTransformIdentity;
+    header.layer.zPosition = ZINDEX_DEFAULT;
+
+  }];
+
+  // If no docked header, bail out
+  if (!currentHeader) {
     return;
   }
 
-  // find the section header that needs to be docked
-  NSInteger firstIndexInView = [[_stickyHeaderIndices firstObject] integerValue] + 1;
-  CGRect scrollBounds = self.bounds;
-  scrollBounds.origin.x += self.contentInset.left;
-  scrollBounds.origin.y += self.contentInset.top;
-
-  NSInteger i = 0;
-  for (UIView *subview in contentView.reactSubviews) {
-    CGRect rowFrame = [RCTCustomScrollView _calculateUntransformedFrame:subview];
-    if (CGRectIntersectsRect(scrollBounds, rowFrame)) {
-      firstIndexInView = i;
-      break;
-    }
-    i++;
+  // Adjust current header to hug the top of the screen
+  CGFloat currentFrameHeight = currentHeader.bounds.size.height;
+  CGFloat currentFrameTop = currentHeader.center.y - currentFrameHeight * currentHeader.layer.anchorPoint.y;
+  CGFloat yOffset = scrollTop - currentFrameTop;
+  if (nextHeader) {
+    // The next header nudges the current header out of the way when it reaches
+    // the top of the screen
+    CGFloat nextFrameHeight = nextHeader.bounds.size.height;
+    CGFloat nextFrameTop = nextHeader.center.y - nextFrameHeight * nextHeader.layer.anchorPoint.y;
+    CGFloat overlap = currentFrameHeight - (nextFrameTop - scrollTop);
+    yOffset -= MAX(0, overlap);
   }
-  NSInteger stickyHeaderii = 0;
-  for (NSNumber *stickyHeaderI in _stickyHeaderIndices) {
-    if ([stickyHeaderI integerValue] > firstIndexInView) {
-      break;
-    }
-    stickyHeaderii++;
-  }
-  stickyHeaderii = MAX(0, stickyHeaderii - 1);
-
-  // Set up transforms for the various section headers
-  NSInteger currentlyDockedIndex = [_stickyHeaderIndices[stickyHeaderii] integerValue];
-  NSInteger previouslyDockedIndex = stickyHeaderii > 0 ? [_stickyHeaderIndices[stickyHeaderii-1] integerValue] : -1;
-  NSInteger nextDockedIndex = (stickyHeaderii < _stickyHeaderIndices.count - 1) ?
-    [_stickyHeaderIndices[stickyHeaderii + 1] integerValue] : -1;
-
-  UIView *currentHeader = contentView.reactSubviews[currentlyDockedIndex];
-  UIView *previousHeader = previouslyDockedIndex >= 0 ? contentView.reactSubviews[previouslyDockedIndex] : nil;
-  CGRect curFrame = [RCTCustomScrollView _calculateUntransformedFrame:currentHeader];
+  currentHeader.transform = CGAffineTransformMakeTranslation(0, yOffset);
+  currentHeader.layer.zPosition = ZINDEX_STICKY_HEADER;
 
   if (previousHeader) {
-    // the previous header is offset to sit right above the currentlyDockedHeader's initial position
-    // (so it scrolls away nicely once the currentHeader locks into position)
-    CGRect previousFrame = [RCTCustomScrollView _calculateUntransformedFrame:previousHeader];
-    CGFloat yOffset = curFrame.origin.y - previousFrame.origin.y - previousFrame.size.height;
+    // The previous header sits right above the currentHeader's initial position
+    // so it scrolls away nicely once the currentHeader has locked into place
+    CGFloat previousFrameHeight = previousHeader.bounds.size.height;
+    CGFloat targetCenter = currentFrameTop - previousFrameHeight * (1.0 - previousHeader.layer.anchorPoint.y);
+    yOffset = targetCenter - previousHeader.center.y;
     previousHeader.transform = CGAffineTransformMakeTranslation(0, yOffset);
+    previousHeader.layer.zPosition = ZINDEX_STICKY_HEADER;
   }
-
-  UIView *nextHeader = nextDockedIndex >= 0 ? contentView.reactSubviews[nextDockedIndex] : nil;
-  CGRect nextFrame = [RCTCustomScrollView _calculateUntransformedFrame:nextHeader];
-
-  if (curFrame.origin.y < scrollBounds.origin.y) {
-    // scrolled off (or being scrolled off) the top of the screen
-    CGFloat yOffset = 0;
-    if (nextHeader && nextFrame.origin.y < scrollBounds.origin.y + curFrame.size.height) {
-      // next frame is bumping me off if scrolling down (or i'm bumping the next one off if scrolling up)
-      yOffset = nextFrame.origin.y - curFrame.origin.y - curFrame.size.height;
-    } else {
-      // standard sticky header position
-      yOffset = scrollBounds.origin.y - curFrame.origin.y;
-    }
-    currentHeader.transform = CGAffineTransformMakeTranslation(0, yOffset);
-    currentHeader.layer.zPosition = ZINDEX_STICKY_HEADER;
-  } else {
-    // i'm the current header but in the viewport, so just scroll in normal position
-    currentHeader.transform = CGAffineTransformIdentity;
-    currentHeader.layer.zPosition = ZINDEX_DEFAULT;
-  }
-
-  // in our setup, 'next header' will always just scroll with the page
-  if (nextHeader) {
-    nextHeader.transform = CGAffineTransformIdentity;
-    nextHeader.layer.zPosition = ZINDEX_DEFAULT;
-  }
-}
-
-+ (CGRect)_calculateUntransformedFrame:(UIView *)view
-{
-  CGRect frame = CGRectNull;
-  if (view) {
-    frame.size = view.bounds.size;
-    frame.origin = CGPointMake(view.layer.position.x - view.bounds.size.width * view.layer.anchorPoint.x, view.layer.position.y - view.bounds.size.height * view.layer.anchorPoint.y);
-  }
-  return frame;
 }
 
 @end
@@ -312,7 +287,7 @@ CGFloat const ZINDEX_STICKY_HEADER = 50;
   _scrollView.centerContent = centerContent;
 }
 
-- (void)setStickyHeaderIndices:(NSArray *)headerIndices
+- (void)setStickyHeaderIndices:(NSIndexSet *)headerIndices
 {
   RCTAssert(_scrollView.contentSize.width <= self.frame.size.width,
            @"sticky headers are not supported with horizontal scrolled views");
@@ -340,14 +315,8 @@ CGFloat const ZINDEX_STICKY_HEADER = 50;
 
 - (void)setContentInset:(UIEdgeInsets)contentInset
 {
-  CGPoint contentOffset = _scrollView.contentOffset;
-
   _contentInset = contentInset;
-  [RCTView autoAdjustInsetsForView:self
-                    withScrollView:_scrollView
-                      updateOffset:NO];
-
-  _scrollView.contentOffset = contentOffset;
+  [self setNeedsLayout];
 }
 
 - (void)scrollToOffset:(CGPoint)offset
@@ -390,6 +359,7 @@ RCT_SCROLL_EVENT_HANDLER(scrollViewDidZoom, RCTScrollEventTypeMove)
 
 - (void)scrollViewDidScroll:(UIScrollView *)scrollView
 {
+  [_scrollView dockClosestSectionHeader];
   [self updateClippedSubviews];
 
   NSTimeInterval now = CACurrentMediaTime();

React/Views/RCTScrollViewManager.m

@@ -41,7 +41,7 @@ RCT_EXPORT_VIEW_PROPERTY(scrollEnabled, BOOL)
 RCT_EXPORT_VIEW_PROPERTY(scrollsToTop, BOOL)
 RCT_EXPORT_VIEW_PROPERTY(showsHorizontalScrollIndicator, BOOL)
 RCT_EXPORT_VIEW_PROPERTY(showsVerticalScrollIndicator, BOOL)
-RCT_EXPORT_VIEW_PROPERTY(stickyHeaderIndices, NSNumberArray)
+RCT_EXPORT_VIEW_PROPERTY(stickyHeaderIndices, NSIndexSet)
 RCT_EXPORT_VIEW_PROPERTY(scrollEventThrottle, NSTimeInterval)
 RCT_EXPORT_VIEW_PROPERTY(zoomScale, CGFloat)
 RCT_EXPORT_VIEW_PROPERTY(contentInset, UIEdgeInsets)