My grandmother is 91 years old and, for about 2 years now, her sight degraded to almost-blindness. She barely sees milky shapes in her central field of vision. It’s supposedly better in the corners of her eyes, but I couldn’t get any reliable confirmation out of her regarding that. So using a telephone is a problem.
In the original post about a cheap way to set the line height in a text view to, say, 150%, the result kind of worked but didn’t look that cool. One issue is that the extra line spacing was exclusively added at the bottom. With the following solution, you’ll get a proper line height with tastefully aligned insertion point and baseline and all.
NSTextView (and UITextView for that matter) have a defaultParagraphStyle attribute where you can set the text’s line height. That works swell – if you display text statically. Once the user can enter something, you can run into trouble: Update 2017-07: I posted a better version without paragraph style attributes that hooks into the NSLayoutManager delegate callbacks for a more consistent and speedy experience!
I like this interactive guide a lot, because it focuses on basic rules of nice-looking typography which result in a quite beautiful example page.
The reference to http://modularscale.com/ was nice, although I seem to fare well with a selection of the traditional scale: 16, 18, 21, 24, 36 (measured in pt; I use ems, though).