This is absolutely possible now, using
+ (NSAttributedString *)attributedStringWithAttachment:(NSTextAttachment *)attachment
See Apple docs here
And this example taken from this other answer:
UITextView *textView = [[UITextView alloc] initWithFrame:CGRectMake(0,0,140,140)];
NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:@"before after"];
NSTextAttachment *textAttachment = [[NSTextAttachment alloc] init];
textAttachment.image = [UIImage imageNamed:@"sample_image.jpg"];
CGFloat oldWidth = textAttachment.image.size.width;
//I'm subtracting 10px to make the image display nicely, accounting
//for the padding inside the textView
CGFloat scaleFactor = oldWidth / (textView.frame.size.width - 10);
textAttachment.image = [UIImage imageWithCGImage:textAttachment.image.CGImage scale:scaleFactor orientation:UIImageOrientationUp];
NSAttributedString *attrStringWithImage = [NSAttributedString attributedStringWithAttachment:textAttachment];
[attributedString replaceCharactersInRange:NSMakeRange(6, 1) withAttributedString:attrStringWithImage];
textView.attributedText = attributedString;
Using the above code will get you an image with text inside a UITextView on iOS 7+. You can/show style the attributed text as you want it and probably set the width of the image to make sure it fits within your textView (as well as setting your own aspect ratio/scale preference)
Here's a quick test image:
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