Learning about data technologies on iOS?

I am the author of Core Data Fundamentals with Swift, CloudKit, iOS Data Persistence: The Big Picture, and eight other courses on Pluralsight.

Deepen your understanding by watching the courses!

Core Data Cheat Sheet for Swift iOS Developers

Updated on July 27, 2016 – Additional Cheats

Having trouble recalling how to perform basic Core Data operations? This cheat sheet is a handy reference to keep you productive with Core Data and Swift!

The code snippets below are here to help jog your memory when it’s been a while since you’ve worked in Core Data. They could also be helpful for newcomers to iOS development, Core Data, and Swift.

One assumption I’m making in this post is that you’ve created NSManagedObject subclasses for your entities to make them easier to work with in a type-safe way. If you need help getting started with that, I’ve written a walk-through to guide you through that process.

Querying

Fetch all entities

1
2
3
4
5
6
7
8
9


// Assuming type has a reference to managed object context

let fetchRequest = NSFetchRequest(entityName: "MyEntity")
do {
    let fetchedEntities = try self.managedObjectContext.executeFetchRequest(fetchRequest) as! [MyEntity]
    // Do something with fetchedEntities
} catch {
    // Do something in response to error condition
}

Fetch maximum of N entities

 1
 2
 3
 4
 5
 6
 7
 8
 9
10


// Assuming type has a reference to managed object context

let fetchRequest = NSFetchRequest(entityName: "MyEntity")
fetchRequest.fetchLimit = 10
do {
    let fetchedEntities = try self.managedObjectContext.executeFetchRequest(fetchRequest) as! [MyEntity]
    // Do something with fetchedEntities
} catch {
    // Do something in response to error condition
}   

Insert a new entity

 1
 2
 3
 4
 5
 6
 7
 8
 9
10


// Assuming encapsulating Type has a reference to managed object context

let newEntity = NSEntityDescription.insertNewObjectForEntityForName("MyEntity", inManagedObjectContext: self.managedObjectContext) as! MyEntity
// Set properties

do {
    try self.managedObjectContext.save()
} catch {
    // Do something in response to error condition
}

Update a single entity

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24


// Assuming type has a reference to managed object context

// Assuming that a specific NSManagedObject's objectID property is accessible
// Alternatively, could supply a predicate expression that's precise enough
// to select only a _single_ entity
let predicate = NSPredicate(format: "objectID == %@", objectIDFromNSManagedObject)

let fetchRequest = NSFetchRequest(entityName: "MyEntity")
fetchRequest.predicate = predicate

do {
    let fetchedEntities = try self.managedObjectContext.executeFetchRequest(fetchRequest) as! [MyEntity]
    fetchedEntities.first?.FirstPropertyToUpdate = NewValue
    fetchedEntities.first?.SecondPropertyToUpdate = NewValue
    // ... Update additional properties with new values
} catch {
    // Do something in response to error condition
}

do {
    try self.managedObjectContext.save()
} catch {
    // Do something in response to error condition
}

Update multiple-entities

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24


// Assuming type has a reference to managed object context

let predicate = NSPredicate(format: "MyEntityAttribute == %@", "Matching Value")

let fetchRequest = NSFetchRequest(entityName: "MyEntity")
fetchRequest.predicate = predicate

do {
    let fetchedEntities = try self.managedObjectContext.executeFetchRequest(fetchRequest) as! [MyEntity]
    
    for entity in fetchedEntities {
        entity.FirstPropertyToUpdate = NewValue
        entity.SecondPropertyToUpdate = NewValue
        // ... Update additional properties with new values
    }
} catch {
    // Do something in response to error condition
}

do {
    try self.managedObjectContext.save()
} catch {
    // Do something in response to error condition
}

Delete a single entity

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24


// Assuming type has a reference to managed object context

// Assuming that a specific NSManagedObject's objectID property is accessible
// Alternatively, could supply a predicate expression that's precise enough
// to select only a _single_ entity
let predicate = NSPredicate(format: "objectID == %@", objectIDFromNSManagedObject)

let fetchRequest = NSFetchRequest(entityName: "MyEntity")
fetchRequest.predicate = predicate

do {
    let fetchedEntities = try self.managedObjectContext.executeFetchRequest(fetchRequest) as! [MyEntity]
    if let entityToDelete = fetchedEntities.first {
        self.managedObjectContext.deleteObject(entityToDelete)
    }
} catch {
    // Do something in response to error condition
}

do {
    try self.managedObjectContext.save()
} catch {
    // Do something in response to error condition
}

Delete multiple-entities

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22


// Assuming type has a reference to managed object context

let predicate = NSPredicate(format: "MyEntityAttribute == %@", "Matching Value")

let fetchRequest = NSFetchRequest(entityName: "MyEntity")
fetchRequest.predicate = predicate

do {
    let fetchedEntities = try self.managedObjectContext.executeFetchRequest(fetchRequest) as! [MyEntity]
    
    for entity in fetchedEntities {
        self.managedObjectContext.deleteObject(entity)
    }
} catch {
    // Do something in response to error condition
}

do {
    try self.managedObjectContext.save()
} catch {
    // Do something in response to error condition
}

Migrate Core Data Model with Automatic Migrations

1
2
3
4
5
6


let model = // set up model

let pscOptions = [NSMigratePersistentStoresAutomaticallyOption : true, NSInferMappingModelAutomaticallyOption : true]
    
let psc = NSPersistentStoreCoordinator(managedObjectModel: model)
try! psc.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: storeURL, options: pscOptions)