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CRUD - Delete - Swift SDK

On this page

  • Delete Realm Objects
  • About The Examples On This Page
  • Delete an Object
  • Delete Multiple Objects
  • Delete All Objects of a Specific Type
  • Delete All Objects in a Realm
  • Delete Map Keys/Values
  • Delete MutableSet Elements
  • Delete the Value of an AnyRealmValue

Deleting Realm Objects must occur within write transactions. For more information about write trasactions, see: Key Concept: Transactions.

If you want to delete the Realm file itself, see: Delete a Realm.

Important
Do not use objects after delete

You cannot access or modify an object after you have deleted it from a realm. If you try to use a deleted object, Realm Database throws an error.

The examples on this page use the following models:

You can delete map entries in a few ways:

  • Use removeObject(for:) to remove the key and the value
  • If the dictionary's value is optional, you can set the value of the key to nil to keep the key.
let realm = try! Realm()
// Find the dog we want to update
let wolfie = realm.objects(Dog.self).where {
$0.name == "Wolfie"
}.first!
// Delete an entry
try! realm.write {
// Use removeObject(for:)
wolfie.favoriteParksByCity.removeObject(for: "New York")
// Or assign `nil` to delete non-optional values.
// If the value type were optional (e.g. Map<String, String?>)
// this would assign `nil` to that entry rather than deleting it.
wolfie.favoriteParksByCity["New York"] = nil
}
XCTAssertNil(wolfie.favoriteParksByCity["New York"])

You can delete specific elements from a MutableSet, or clear all of the elements from the set. If you are working with multiple sets, you can also remove elements in one set from the other set; see: Update a MutableSet Property.

let realm = try! Realm()
// Record a dog's name and list of cities he has visited.
let dog = Dog()
dog.name = "Maui"
let dogCitiesVisited = ["New York", "Boston", "Toronto"]
try! realm.write {
realm.add(dog)
dog.citiesVisited.insert(objectsIn: dogCitiesVisited)
}
XCTAssertEqual(dog.citiesVisited.count, 3)
// Later... we decide the dog didn't really visit Toronto
// since the plane just stopped there for a layover.
// Remove the element from the set.
try! realm.write {
dog.citiesVisited.remove("Toronto")
}
XCTAssertEqual(dog.citiesVisited.count, 2)
// Or, in the case where the person entered the data for
// the wrong dog, remove all elements from the set.
try! realm.write {
dog.citiesVisited.removeAll()
}
XCTAssertEqual(dog.citiesVisited.count, 0)

To delete the value of an AnyRealmValue, set it to .none.

let realm = try! Realm()
// Wolfie's companion is "Fluffy the Cat", represented by a string.
// Fluffy has gone to visit friends for the summer, so Wolfie has no companion.
let wolfie = realm.objects(Dog.self).where {
$0.name == "Wolfie"
}.first!
try! realm.write {
// You cannot set an AnyRealmValue to nil; you must set it to `.none`, instead.
wolfie.companion = .none
}
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