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I'd like to add a QuickLook Preview Extension to my Mac app (AppKit), however I don't see a template for the extension in Xcode 13 under macOS (though there is a templete for iOS). This seems to be a change as there was an extension template for Mac offered in Xcode 12. Is this simply an oversight, or are Quick Look Preview Extensions no longer a thing on the Mac?

My app processes numbers, and depends on the grouping separator on the system locale (Locale.current). The user can set a completely custom symbol as their number separator in the macOS System Preferences. In my tests, I need to verify that custom grouping separators on Locale objects work correctly. But I can't set a custom grouping separator as the groupingSeparator property on Locale is read-only:    /// For example, for "en_US", returns ",".   public var groupingSeparator: String? { get } How do I create a Locale object for testing purposes, that will simulate a custom locale the user might have configured in the System Preferences?