Changing the font of the selected text in Objective-C - objective-c

Question

I'm trying to create a custom “Change font” NSPopupButton for a Mac App (not an iOS App). I can detect a change in font selection:
long fontItemIndex = [fontPopup indexOfSelectedItem];
NSMenuItem *fontItem = [fontPopup itemAtIndex:(int)selectedFontItemIndex];
NSString *fontName = [selectedFontItem title];
Given this NSString of a font name, I cannot seem to find out how to actually change the selected text in my NSTextView textView to this new font.
I'm simply dazzled by the official documentation: it seems convertFont:toFamily: is what I need. When I do this:
NSFont *font = [NSFont fontWithName:fontName size:12.0];
[textView setFont:font];
It sets all text in the text view, not just the selected text. But when I do this:
NSFontManager *fontManager = [NSFontManager sharedFontManager];
[fontManager convertFont:[fontManager selectedFont] toFamily:fontName];
it doesn't do a thing. What am I missing?

Answer 1

Inside a NSTextView is a NSTextStorage (a subclass of NSAttributedString) and you’ll have to modify the attribute named NSFontAttributeName.
First get the range where you want to change the font attribute:
NSRange selection = textView.selectedRange;
Now add the font attribute to the selection:
NSFont *font = [NSFont fontWithName:fontName size:12.0f];
[self.textView.textStorage addAttributes:#{NSFontAttributeName: font}
range:selection];
Depending on the contents of your NSPopUpButton it should be enough to call fontWithName:size: with title as the font name to get the just selected font. But if the method you already do doesn’t work, you’ll probably have to get a specific font from the font family name. availableMembersOfFontFamily: on NSFontManager will give you a list of all available fonts. You can use one of them to initialize a specific font.

Answer 2

Take a look at the setFont:range: method on NSText, the superclass of NSTextView.
(The ranges, of course, come from the selectedRanges property on NSTextView.)

Answer 3

This was all I needed to change all the text in my textview.
[textview setFont:[NSFont fontWithName:#"Courier" size:14]];