app/internal/window: macOS clipboard support

Updates gio#31

Signed-off-by: Elias Naur <mail@eliasnaur.com>

app/internal/window/os_darwin.m

@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: Unlicense OR MIT
 
 @import Dispatch;
+@import Foundation;
 
 #include "_cgo_export.h"
 
@@ -9,3 +10,13 @@ void gio_wakeupMainThread(void) {
 		gio_dispatchMainFuncs();
 	});
 }
+
+NSUInteger gio_nsstringLength(CFTypeRef cstr) {
+	NSString *str = (__bridge NSString *)cstr;
+	return [str length];
+}
+
+void gio_nsstringGetCharacters(CFTypeRef cstr, unichar *chars, NSUInteger loc, NSUInteger length) {
+	NSString *str = (__bridge NSString *)cstr;
+	[str getCharacters:chars range:NSMakeRange(loc, length)];
+}