< How to filter Core Data fetch requests using a predicate | How to delete Core Data objects from SwiftUI views > |
Updated for Xcode 13.3
Saving Core Data objects in SwiftUI works in exactly the same way it works outside of SwiftUI: get access to the managed object context, create an instance of your type inside that context, then save the context when you’re ready.
If you followed my Core Data and SwiftUI set up instructions, you’ve already injected your managed object context into the SwiftUI environment.
Anywhere you need to create Core Data objects you should add an @Environment
property to ContentView
to read the managed object context right out:
@Environment(\.managedObjectContext) var managedObjectContext
Next, go ahead and create an instance of your Core Data entity class wherever you need, referencing that managedObjectContext
. In my example setup, we have a ProgrammingLanguage entity with name
and creator
properties, so we could create one of those inside a SwiftUI button action like this:
Button("Insert example language") {
let language = ProgrammingLanguage(context: managedObjectContext)
language.name = "Python"
language.creator = "Guido van Rossum"
// more code here
}
Finally, save the context whenever is appropriate – that might be immediately, after a group of objects have been added, when the state of your app changes, and so on.
If you’re using my PersistenceController
setup code from earlier, replace // more code here
with this:
PersistenceController.shared.saveContext()
If you’re not, use this code instead:
do {
try managedObjectContext.save()
} catch {
// handle the Core Data error
}
Remember, for general saves that don’t directly follow creating a new object, it’s usually worth adding a check to see whether your managed object context has any changes:
if managedObjectContext.hasChanges {
SPONSORED Fernando's book will guide you in fixing bugs in three real, open-source, downloadable apps from the App Store. Learn applied programming fundamentals by refactoring real code from published apps. Hacking with Swift readers get a $10 discount!
Sponsor Hacking with Swift and reach the world's largest Swift community!
Link copied to your pasteboard.