We update all our books with major releases of Swift and iOS. Ebook updates are free of charge, but paper updates will require a new purchase.
Where we rewrite a book extensively, it will be charged as a new book, not an update. This will be announced on the book's page once we start the rewrite.
From time to time, we might retire a book. All updates will stop, and the book will spend its last days on quiet library shelves.