Core Data overview in iOS Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a Core Data context from the persistent container.

iOS Swift

let context = persistentContainer.[1]

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AdefaultContext

BviewContext

CbackgroundContext

DmainContext

Attempts:

3 left

💡 Hint

Common Mistakes

Using backgroundContext instead of viewContext for UI updates.

Trying to access a context property that does not exist.

The viewContext is the main managed object context used for UI updates in Core Data.

2fill in blank

medium

Complete the code to save changes in the Core Data context.

iOS Swift

do {
  try context.[1]()
} catch {
  print("Save failed")
}

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Acommit

Bpersist

Csave

Dstore

Attempts:

3 left

💡 Hint

Common Mistakes

Using commit() which does not exist.

Forgetting to use try with save().

Calling save() on the context commits changes to the persistent store.

3fill in blank

hard

Fix the error in fetching Core Data objects by completing the fetch request code.

iOS Swift

let fetchRequest = NSFetchRequest<NSManagedObject>(entityName: [1])
let results = try context.fetch(fetchRequest)

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AUserEntity

BuserEntity

C"userEntity"

D"UserEntity"

Attempts:

3 left

💡 Hint

Common Mistakes

Not using quotes around the entity name string.

Using incorrect capitalization.

The entity name must be a string literal matching the Core Data model entity name exactly, including case.

4fill in blank

hard

Fill both blanks to create a new managed object and set its attribute.

iOS Swift

let entity = NSEntityDescription.entity(forEntityName: [1], in: context)!
let newObject = NSManagedObject(entity: entity, insertInto: [2])
newObject.setValue("John", forKey: "name")

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A"Person"

Bcontext

CpersistentContainer

DviewContext

Attempts:

3 left

💡 Hint

Common Mistakes

Using persistentContainer instead of context for insertion.

Not quoting the entity name.

Use the entity name as a string and insert the new object into the current context.

5fill in blank

hard

Fill all three blanks to filter fetch results by a condition.

iOS Swift

let fetchRequest = NSFetchRequest<NSManagedObject>(entityName: [1])
fetchRequest.predicate = NSPredicate(format: "[2] == %@", [3])
let results = try context.fetch(fetchRequest)

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A"Person"

Bage

C30

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Using attribute names without quotes in the format string.

Passing a string instead of a number for age.

The fetch request uses the entity name "Person" and filters where the attribute "age" equals 30.