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How to add Core Data objects from SwiftUI views

Paul Hudson    @twostraws   

Updated for Xcode 12.0

Saving Core Data Objects in SwiftUI 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(action: {
    let language = ProgrammingLanguage(context: self.managedObjectContext)
    language.name = "Python"
    language.creator = "Guido van Rossum"
    // more code here
}) {
    Text("Insert example language")
}

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. To do that, replace // more code here with this:

do {
    try self.managedObjectContext.save()
} catch {
    // handle the Core Data error
}

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, like this:

if self.managedObjectContext.hasChanges {
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