In Core Data, faults are placeholders, or “unrealized objects”. They are small objects which refer to other NSManagedObjects, which are fetched into memory only as needed. This faulting mechanism is designed to enhance performance and reduce memory use.
What is faulting in IOS?
Faulting reduces your application’s memory usage by keeping placeholder objects (faults) in the persistent store. A related feature called uniquing ensures that, in a given managed object context, you never have more than one managed object to represent a given record.
What is data fault in Core Data?
Core Data hands us a set of objects, but it hasn’t actually fetched the tags itself. The data of each tag is a fault. The data is fetched the moment we access it. When Core Data tries to fetch data from the persistent store that no longer exists, it tells you it is unable to fulfill the fault.
What is Core Data fault Swift?
The idea is simple, only load data when it’s needed. To make faulting work, Core Data does a bit of magic under the hood by creating custom subclasses at compile time that represent the faults. The project uses Swift 2.1, which means that you need Xcode 7.1 or higher to satisfy the compiler.
What are Core Data delete rules?
A delete rule defines what happens when the record that owns the relationship is deleted. Select the notes relationship of the Category entity and open the Data Model Inspector on the right. By default, the delete rule of a relationship is set to nullify….Delete Rules
- No Action.
- Nullify.
- Cascade.
- Deny.
What is inverse relationship in Core Data?
Inverse relationships enable Core Data to propagate change in both directions when an instance of either the source or destination type changes. Every relationship must have an inverse. When creating relationships in the Graph editor, you add inverse relationships between entities in a single step.
Is Core Data thread safe?
Core Data is designed to work in a multithreaded environment. However, not every object under the Core Data framework is thread safe. To use Core Data in a multithreaded environment, ensure that: Managed object contexts are bound to the thread (queue) that they are associated with upon initialization.
Is Core Data relational?
Core Data is not a relational database or a relational database management system. It can use SQLite as one of its persistent store types, but it is not in and of itself a database. You could set up Core Data to just use an in-memory store just to get the change tracking and management features without persistence.
Should have an inverse Core Data?
A quick Google suggests you should use them: An inverse relationship doesn’t just make things more tidy, it’s actually used by Core Data to maintain data integrity. You should typically model relationships in both directions, and specify the inverse relationships appropriately.
Is Core Data thread safe in iOS?
Is Core Data thread safe? Yes and no. Even though the framework originated in a time where computers with multicore processors were rare, Core Data is designed to operate in a multithreaded environment. In other words, it works fine on the latest iPhone and a Mac Pro with 28 cores.
What is iOS Core Data?
Core Data is an object graph and persistence framework provided by Apple in the macOS and iOS operating systems. It was introduced in Mac OS X 10.4 Tiger and iOS with iPhone SDK 3.0. It allows data organized by the relational entity–attribute model to be serialized into XML, binary, or SQLite stores.
What is objectfaulting in core data?
Faulting allows Core Data to put boundaries on the object graph. Because a fault is not realized, a managed object fault consumes less memory, and managed objects related to a fault are not required to be represented in memory at all. To illustrate, consider an application that allows a user to fetch and edit details about a single employee.
How do I fire faults in corecore data?
Core Data automatically fires faults when a persistent property (such as firstName) of a fault is accessed. However, firing faults individually can be inefficient, and there are better strategies for getting data from the persistent store (see Decreasing Fault Overhead ).
What is a fault in core data?
Faults are an essential component of Core Data. Even though the term sounds ominous, faults are inherent to the life cycle of a Core Data record.
What is the difference between managed object fault and relationship fault?
A managed object fault is an instance of the appropriate class, but its persistent variables are not yet initialized. A relationship fault is a subclass of the collection class that represents the relationship. Faulting allows Core Data to put boundaries on the object graph.
