Create Photo Book in Photos? Or a calendar? Or what to order through the integrated printing service from Apple? Be quick, because Apple stops with its printed products. When you start a new project in Photos (ie a photo book, calendar or similar), you will receive a notification that you still have the chance to place your order until 30 September 2018. Apple also recommends downloading project extensions from other developers via the Mac App Store, so that you can continue to create projects. For now, however, it is still possible to create a new project – and also finish it.
The printed products at Apple have existed for a long time. His introduction celebrated the service in the first version of iPhoto that came out in 2002. First you could only order photo prints, but soon photo albums, photo books and calendars followed. The switch to the new Photos program also survived the printing service. Remarkably, it was never possible to create or order printed products via iOS. Also in macOS Mojave all references to the printing service have been deleted.
If you go to the Mac App Store via the notification in Photos, you will receive alternative services.
The advantage of a project extension is that it is integrated in Photos in contrast to complete photo book programs. So you never leave the accustomed user interface, and you have instant access to all your photos from iCloud Photo Library. However, within the project extension, developers have every freedom to provide a unique experience. Also the handling of the order and payment is done entirely at the alternative service.