Search correct paths for fonts on Apple platforms.

Use the Foundation API to get the list of "Library" directories
and look in each of them for a "Fonts" directory.

This handles the need to search a variety of paths on macOS
to find fonts in the various standard locations like "~/Library/Fonts",
"/System/Library/Fonts", "/Library/Fonts", "/Network/Library/Fonts",
etc.

Fixes #50.

fontique/Cargo.toml

@@ -38,6 +38,8 @@ wio = "0.2.2"
 [target.'cfg(target_vendor="apple")'.dependencies]
 core-text = "20.1.0"
 core-foundation = "0.9.4"
+objc2 = { version = "0.5.2" }
+objc2-foundation = { version = "0.2.2", features = ["NSArray", "NSEnumerator", "NSPathUtilities", "NSString"] }
 
 [target.'cfg(not(any(target_vendor="apple", target_family="windows")))'.dependencies]
 fontconfig-cache-parser = "0.2.0"

fontique/src/backend/coretext.rs

@@ -6,6 +6,10 @@ use super::{
 };
 use alloc::sync::Arc;
 use hashbrown::HashMap;
+use objc2::runtime::Bool;
+use objc2_foundation::{
+    NSSearchPathDirectory, NSSearchPathDomainMask, NSSearchPathForDirectoriesInDomains,
+};
 use {
     core_foundation::{
         base::{CFRange, TCFType},
@@ -37,7 +41,17 @@ pub struct SystemFonts {
 
 impl SystemFonts {
     pub fn new() -> Self {
-        let scanned = scan::ScannedCollection::from_paths(Some("/System/Library/Fonts"), 8);
+        let paths = unsafe {
+            NSSearchPathForDirectoriesInDomains(
+                NSSearchPathDirectory::NSLibraryDirectory,
+                NSSearchPathDomainMask::NSAllDomainsMask,
+                Bool::YES,
+            )
+            .as_ref()
+            .iter()
+            .map(|p| format!("{p}/Fonts/"))
+        };
+        let scanned = scan::ScannedCollection::from_paths(paths, 8);
         let name_map = scanned.family_names;
         let mut generic_families = GenericFamilyMap::default();
         for (family, names) in DEFAULT_GENERIC_FAMILIES {