Realm Swift Sort By If Object Exists

Given the following example code...

class Example: Object {
     dynamic var other: OtherObj? // Some other object type

let realm = Realm()
let result = realm.object(Example.self).sorted( ??? )

How would one perform a sort so that all Example objects with other as nil are sorted before all other objects with other as not nil and still have the result be of type Results<Example>?