How to delete a SwiftData object 관련

SwiftData by Example

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How to delete a SwiftData object | SwiftData by Example

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How to delete a SwiftData object

Updated for Xcode 15

Deleting a SwiftData object takes two steps: calling delete() on your model context, passing in the object you want to delete, then saving the changes, either with an explicit call to save() or waiting for the autosave to trigger if you have it enabled.

So, for single objects you’d write code like this:

List(students) { student in
    Text(student.name)
        .swipeActions {
            Button("Delete", systemImage: "trash", role: .destructive) {
                modelContext.delete(student)
            }
        }
}

If you were working with a collection of objects, you’d need a for loop like this one:

func delete(_ indexSet: IndexSet) {
    for i in indexSet {
        let student = students[i]
        modelContext.delete(student)
    }
}

If you want to delete all objects of a particular model type, you should use the delete(model:) overload, like this:

do {
    try modelContext.delete(model: School.self)
} catch {
    print("Failed to delete all schools.")
}

And if you want to delete only a subset of objects, you should use delete(model:) with a predicate, like this:

try modelContext.delete(model: School.self, where: #Predicate { school in
    school.students.isEmpty
})

Important

Calling delete() marks your object for deletion, but doesn’t actually complete the deletion until a save happens. Between those two states your object is stored in the deletedModelsArray of your property, and if the deletion is rolled back the object will be moved back from deletedModelsArray to your live data. Alternatively, if you have autosave disabled and don’t call save() manually, your deletions will automatically be rolled back.

If you’re deleting an object that has relationships, SwiftData will act on those relationships as part of the deletion – that’s the .nullify delete rule by default, but you might also have requested .cascade or one of the others. If you have a cascade delete in place, SwiftData will automatically continue the cascade down through all objects in a chain: deleting a School might delete all its students, and deleting students might delete all their exam results, for example.