Introduce an attributesForTailTruncationString property.

This property will allow callers to add custom text attributes to the `tailTruncationString` property in `NIAttributedLabel`.

PiperOrigin-RevId: 413440335

src/attributedlabel/src/NIAttributedLabel.h

@@ -122,6 +122,7 @@ extern NSString* const NIAttributedLabelLinkAttributeName; // Value is an NSText
 @property (nonatomic, strong) UIColor*      highlightedLinkBackgroundColor; // Default: [UIColor colorWithWhite:0.5 alpha:0.5
 @property (nonatomic)         BOOL          linksHaveUnderlines;            // Default: NO
 @property (nonatomic, copy)   NSDictionary* attributesForLinks;             // Default: nil
+@property (nonatomic, copy)   NSDictionary* attributesForTailTruncationString;  // Default: nil
 @property (nonatomic, copy)   NSDictionary* attributesForHighlightedLink;   // Default: nil
 @property (nonatomic)         CGFloat       lineHeight;
 

src/attributedlabel/src/NIAttributedLabel.m

@@ -707,6 +707,14 @@ - (void)setLinksHaveUnderlines:(BOOL)linksHaveUnderlines {
   }
 }
 
+- (void)setAttributesForTailTruncationString:(NSDictionary *)attributesForTailTruncationString {
+  if (_attributesForTailTruncationString != attributesForTailTruncationString) {
+    _attributesForTailTruncationString = attributesForTailTruncationString;
+
+    [self attributedTextDidChange];
+  }
+}
+
 - (void)setAttributesForLinks:(NSDictionary *)attributesForLinks {
   if (_attributesForLinks != attributesForLinks) {
     _attributesForLinks = attributesForLinks;
@@ -1419,7 +1427,7 @@ - (NSMutableAttributedString *)mutableAttributedStringWithAdditions {
         NSInteger index = MAX((NSInteger)0, MIN((NSInteger)(attributedString.length - 1), labelImage.index));
         attributes = [attributedString attributesAtIndex:index effectiveRange:NULL];
       }
-      
+
       UIFont *font = attributes[NSFontAttributeName];
       if (font) {
         labelImage.fontAscent = font.ascender;
@@ -1438,7 +1446,7 @@ - (NSMutableAttributedString *)mutableAttributedStringWithAdditions {
         if (font) {
           [space addAttribute:NSFontAttributeName value:font range:NSMakeRange(0, space.length)];
         }
-        
+
         CFRange range = CFRangeMake(0, 1);
         CFMutableAttributedStringRef spaceString = (__bridge_retained CFMutableAttributedStringRef)space;
         CFAttributedStringSetAttribute(spaceString, range, kCTRunDelegateAttributeName, delegate);
@@ -1622,12 +1630,17 @@ - (void)drawAttributedString:(NSAttributedString *)attributedString rect:(CGRect
 
         NSAttributedString* tokenAttributedString;
         {
+          NSMutableDictionary *mutableTokenAttributes = [NSMutableDictionary new];
           NSDictionary *tokenAttributes = [attributedString attributesAtIndex:truncationAttributePosition
                                                                effectiveRange:NULL];
+          [mutableTokenAttributes addEntriesFromDictionary:tokenAttributes];
+          [mutableTokenAttributes addEntriesFromDictionary:_attributesForTailTruncationString];
           NSString* tokenString = ((nil == self.tailTruncationString)
                                    ? kEllipsesCharacter
                                    : self.tailTruncationString);
-          tokenAttributedString = [[NSAttributedString alloc] initWithString:tokenString attributes:tokenAttributes];
+          tokenAttributedString =
+              [[NSAttributedString alloc] initWithString:tokenString
+                                              attributes:mutableTokenAttributes];
         }
 
         CTLineRef truncationToken = CTLineCreateWithAttributedString((__bridge CFAttributedStringRef)tokenAttributedString);
@@ -1728,7 +1741,7 @@ - (void)drawStrikethroughOverGlyphRun:(CTRunRef)run
   UIFont *font = CFDictionaryGetValue(attributes, kFontAttributeKey);
   font = font ?: self.font;
   CGFloat strikeHeight = font.xHeight / 2.f + (*firstGlyphPosition).y;
-  
+
   // Adjustment for multiline elements.
   CGPoint pt = CGContextGetTextPosition(ctx);
   strikeHeight += pt.y;