Mapping Models - Intermediate Core Data - raywenderlich.com скачать в хорошем качестве

Mapping Models - Intermediate Core Data - raywenderlich.com

Level up your Core Data skills by watching this Core Data course for intermediate developers. View the updated course over here: https://videos.raywenderlich.com/cour... --- About www.raywenderlich.com: raywenderlich.com is a website focused on developing high quality programming tutorials. Our goal is to take the coolest and most challenging topics and make them easy for everyone to learn – so we can all make amazing apps. We are also focused on developing a strong community. Our goal is to help each other reach our dreams through friendship and cooperation. As you can see below, a bunch of us have joined forces to make this happen: authors, editors, subject matter experts, app reviewers, and most importantly our amazing readers! --- Core Data is a framework that you use to manage the model layer objects in your application. It provides generalized and automated solutions to common tasks associated with object life cycle and object graph management, including persistence. Core Data typically decreases by 50 to 70 percent the amount of code you write to support the model layer. This is primarily due to the following built-in features that you do not have to implement, test, or optimize: Change tracking and built-in management of undo and redo beyond basic text editing. Maintenance of change propagation, including maintaining the consistency of relationships among objects. Lazy loading of objects, partially materialized futures (faulting), and copy-on-write data sharing to reduce overhead. Automatic validation of property values. Managed objects extend the standard key-value coding validation methods to ensure that individual values lie within acceptable ranges, so that combinations of values make sense. Schema migration tools that simplify schema changes and allow you to perform efficient in-place schema migration. Optional integration with the application’s controller layer to support user interface synchronization. Grouping, filtering, and organizing data in memory and in the user interface. Automatic support for storing objects in external data repositories. Sophisticated query compilation. Instead of writing SQL, you can create complex queries by associating an NSPredicate object with a fetch request. Version tracking and optimistic locking to support automatic multiwriter conflict resolution. Effective integration with the macOS and iOS tool chains. Core Data provides support for managing changes to a managed object model as your application evolves. You can only open a Core Data store using the managed object model used to create it. Changing a model will therefore make it incompatible with (and so unable to open) the stores it previously created. If you change your model, you therefore need to change the data in existing stores to new version—changing the store format is known as migration. To migrate a store, you need both the version of the model used to create it, and the current version of the model you want to migrate to. You can create a versioned model that contains more than one version of a managed object model. Within the versioned model you mark one version as being the current version. Core Data can then use this model to open persistent stores created using any of the model versions, and migrate the stores to the current version. To help Core Data perform the migration, though, you may have to provide information about how to map from one version of the model to another. This information may be in the form of hints within the versioned model itself, or in a separate mapping model file that you create.