iOS textkit NSLayoutManagerDelegate

[MrFusion]

I am breaking my head over something which works fine under Mac OS X, but not on iOS.

My goal is to do text folding. That means hiding a bunch of characters and showing a image instead. That can be done with an NSTextAttachment and with custom glyph mapping. On iOS I can only hide the characters but not show the text attachment. I am happy to entertain and try out all your suggestions on showing the attachment.

Attachements can be added to a regular string by:

[NSString stringWithFormat:@"attachment: _%C_",(unichar)NSAttachmentCharacter]

The NSAttachmentCharacter has a glyph index of 65535 (according to logging).

-(NSUInteger)layoutManager:(NSLayoutManager *)layoutManager
	  shouldGenerateGlyphs:(const CGGlyph *)glyphs
				properties:(const NSGlyphProperty *)props
		  characterIndexes:(const NSUInteger *)charIndexes
					  font:(UIFont *)aFont
			 forGlyphRange:(NSRange)glyphRange
{
	//buffers
	NSInteger size = glyphRange.length;
	CGGlyph nullGlyph = kCGFontIndexInvalid;
	CGGlyph *buffer = malloc(sizeof(CGGlyph) * size);
	memset_pattern4(buffer, &nullGlyph, size);

	NSGlyphProperty nullGlyphProperty = NSGlyphPropertyNull;
	NSGlyphProperty *propBuffer = malloc(sizeof(NSGlyphProperty) * size);
	memset_pattern4(propBuffer, &nullGlyphProperty, size);
	

        NSUInteger index = 0;
	while (index < glyphRange.length)
	{
		id attribute = [[layoutManager textStorage] attribute:@"FoldText"
													  atIndex:charIndexes[index]
										longestEffectiveRange:&effectiveRange
													  inRange:NSMakeRange(0, [[layoutManager textStorage] length])];
		
		if (attribute && [attribute boolValue])
		{
			UTF16Char ellipsis = NSAttachmentCharacter;
			CGGlyph attachmentGlyph;
			CTFontGetGlyphsForCharacters((CTFontRef) aFont, &ellipsis, &attachmentGlyph, 1);
			
			if (effectiveRange.location == charIndexes[index])
			{
				NSLog(@"found: %hu | %d ||%d | %d | %d || %d",
					  glyphs[index],
					  props[index],
					  NSAttachmentCharacter,
					  attachmentGlyph,
					  NSGlyphPropertyControlCharacter,
					  kCGGlyphMax);
				
				
				buffer[index] = 65535; //magic number for the glyph corresponding with NSAttachmentCharacter?  
				propBuffer[index] = NSGlyphPropertyControlCharacter;
				
				[layoutManager setAttachmentSize:CGSizeMake(100, 100)
								   forGlyphRange:NSMakeRange(glyphRange.location+index, 1)];
				
			}
//			else//not necessary => see buffer alloc
//			{
//				propBuffer[index] = NSGlyphPropertyNull;
//			}
		}
		else
		{
			buffer[index] = glyphs[index];
			propBuffer[index] = props[index];
		}
		index++;
	}

	[layoutManager setGlyphs:buffer
				  properties:propBuffer
			characterIndexes:charIndexes
						font:aFont
			   forGlyphRange:glyphRange];
	
         //fixme: leak
	//	free(propBuffer);
	//	free(buffer);
	
	
	return glyphRange.length;