Creates an NSTextAttachment the takes up the entire width of the line fragment (while maintaining its aspect ratio). Instead of a simple image, any UIView (that has a (CGFloat)heightThatFits method) will work.

WPTextAttachment.h

//
//  WPTextAttachment.h
//  ReadArticle
//
//  Created by Moore, Stuart on 12/27/13.
//  Copyright (c) 2013 The Washington Post. All rights reserved.
//

#import <UIKit/UIKit.h>

@class NativeDownloadable, WPDownloadableItemView;

@interface WPTextAttachment : NSTextAttachment

@property (nonatomic, weak) UIView *view;

@property (nonatomic, assign) CGSize size;

@end

WPTextAttachment.m

//
//  WPTextAttachment.m
//  ReadArticle
//
//  Created by Moore, Stuart on 12/27/13.
//  Copyright (c) 2013 The Washington Post. All rights reserved.
//

#import "WPTextAttachment.h"
#import "WPTextContainer.h"

@implementation WPTextAttachment

- (CGRect)attachmentBoundsForTextContainer:(WPTextContainer*)container
                      proposedLineFragment:(CGRect)lineFrag
                             glyphPosition:(CGPoint)position
                            characterIndex:(NSUInteger)index {
    CGFloat width = lineFrag.size.width;
    
    CGSize size = self.size;
    CGFloat ratio = (size.height == 0 || isnan(size.height))? 0 : size.width / size.height;
    CGFloat height = self.view? self.view.heightThatFits : ((ratio == 0)? 0 : width / ratio);
    width = (height == 0)? width = 0 : width;
    
    self.bounds = CGRectMake(0, 0, ceilf(width), ceilf(height));
    
    if(self.view.superview != container.view)
        [container.view addSubview:self.view];
    
    CGRect lineRect = lineFrag;
    lineRect.size = self.bounds.size;
    self.view.frame = CGRectIntegral(lineRect);
    
    return self.bounds;
}

- (UIImage*)imageForBounds:(CGRect)bounds textContainer:(WPTextContainer*)container characterIndex:(NSUInteger)index {
    return nil;
}

@end

WPTextContainer.h

//
//  WPTextContainer.h
//  WashPost
//
//  Created by Moore, Stuart on 1/16/14.
//  Copyright (c) 2014 Washington Post. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface WPTextContainer : NSTextContainer

@property (nonatomic, weak) UITextView *view; // you need to set this up.

@end