This is for DTCoreText. I fiddled some time with this.. I wanted to get a custom view (not html based) into a label. I found I had forgotten setting the CTRunDelegate :/ So it wasn't resized ok. now it works ;)

NSAttributedString+DDTextAttachment.mm

  @implementation NSAttributedString (DTTextAttachment)

	+ (instancetype)attributedStringWithTextAttachment:(DTTextAttachment*)attachment {
	    NSMutableDictionary *mAttributes = [NSMutableDictionary dictionary];

	    [mAttributes setObject:attachment forKey:NSAttachmentAttributeName];
	    
	#if DTCORETEXT_SUPPORT_NS_ATTRIBUTES && TARGET_OS_IPHONE
	    // need run delegate for sizing
	    CTRunDelegateRef embeddedObjectRunDelegate = createEmbeddedObjectRunDelegate(attachment);
	    [mAttributes setObject:CFBridgingRelease(embeddedObjectRunDelegate) forKey:(id)kCTRunDelegateAttributeName];
	#endif
	    
	    NSString *s = [NSString stringWithCharacters:(unichar*)NSAttachmentCharacter length:1];
	    return [[NSAttributedString alloc] initWithString:s attributes:mAttributes];
	}

	@end