Updating a relationship isn't difficult either. We now have a good grasp of the basics of Core Data and it's time to start working with the framework by creating an application that leverages its power. The rest of the code block should look familiar. We create another Person record, set its attributes, and set it as a child of newPerson by asking Core Data for a mutable set for the key children and adding the new record to the mutable set. We also have operators for string comparison, CONTAINS, LIKE, MATCHES, BEGINSWITH, and ENDSWITH. Predicates also make it very easy to fetch records based on their relationship. The above predicate works as expected, because %K is a variable argument substitution for a key path, not just a key. It's time to take your Core Data skills up a notch: we're going to add a second entity called Author, and link that entity to our existing Commit entity. This is very easy to do and the syntax will remind some of you of SQL. Lead discussions. Please make both strings, and make sure both are not marked as optional. The class we'll be working with is NSPredicate. This Core data Hindi tutorial on one to many relationship tutorials offers in-depth details about core data relationship in swift for beginners and experienced developers. Create a new relationship and name it spouse. The Userentity has two attributes: 1. firstName of type String 2. lastName of type String It also has a relationship, account, with the Account … Sort descriptors are great and easy to use, but predicates are what really makes fetching powerful in Core Data. Persistent Storage has become an essential part of the majority of iOS apps that are released today. Let's start with a simple example in which we see how to sort the results returned by a fetch request. The output shows that the order of the sort descriptors in the array is important. Because every attribute of the Address entity is marked as optional, we don't need to assign a value to each attribute. • Fetched property – This provides an alternative to defining relationships. Update Policy There is a cost to creating and maintaining each index, which means you need to choose carefully which attributes should be index. We then create another sort descriptor with a key of age and add it to the array of sort descriptors that we pass to setSortDescriptors:. So, as long as your changes are strictly additive, NSPersistentContainer will take care of all the work. A person is linked to one or more addresses and an address is linked to one or more persons. This needs to set up and execute a new NSFetchRequest (using an == NSPredicate to match the name), then use the result if there is one. The following code block accomplishes the same result by setting the father attribute of anotherChildPerson. Because setSortDescriptors: accepts an array, it is possible to pass in more than one sort descriptor. To create a person, update the application:didFinishLaunchingWithOptions: method as shown below. Core Data-Florian Kugler 2016-12-18 Core Data best practices by example: from simple persistency to multithreading and syncing This book strives to give you clear guidelines for how to get the most out of Core Data while avoiding the pitfalls of this flexible and powerful framework. The AppDelegate.swift file with Core Data Stack code; Core Data Stack . In the previous article, we learned about NSManagedObject and how easy it is to create, read, update, and delete records using Core Data. This will allow us to attach an author to every commit, but also to find all commits that belong to a specific author. Let's start by fetching every member of the Doe family. There are a couple of notable built-in features such as 1. change tracking of data, 2. undo and redo to data 3. In addition to = and ==, which are identical as far as Core Data is concerned, there's also >= and =>, <= and =>, != and <>, and > and <. So, go back to the data model, and choose Editor > Create NSManagedObject Subclass again. Glossary While working on my latest project I have decided to write a tutorial about Core Data Relationships between Entities.. We call save: on the managed object context of the newPerson object to propagate the changes to the persistent store. But when you find a particular fetch request is happening slowly, chances are it's because you need to index an attribute. In the following example, we fetch every person whose father's name is equal to Bart. The records are first sorted by their last name and then by their age. Collaborate. The first step in working with Core Data is to create a data model file. Core Data best practices by example: from simple persistency to multithreading and syncing. Durian is a fruit that's very popular in south-east Asia, particularly Malaysia, Singapore and Thailand. Open the data model and create two entities, Account and User. NEW: Start my new Ultimate Portfolio App course with a free Hacking with Swift+ trial!