CRUD - Delete - Swift SDK
On this page
Delete Realm Objects
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.
About The Examples On This Page
The examples on this page use the following models:
Delete an Object
Delete Multiple Objects
Delete All Objects of a Specific Type
Delete All Objects in a Realm
Delete Map Keys/Values
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
nilto 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"])
Delete MutableSet Elements
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)
Delete the Value of an AnyRealmValue
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 }