View coordinator/delegate disappear function? - ios

Question

Is there a function for the view coordinator/delegate for when the view disappears?
I'm trying to create a textview that "autosaves" notes people enter into core data. Basically it just waits 2 seconds since the last textViewDidChange and then saves the data.
It uses a simple Boolean variable for the "queue" to ensure that it won't try and save multiple times within those 2 seconds.
Here is the code for that:
struct BodyTextView: UIViewRepresentable {
#Environment(\.managedObjectContext) var managedObjectContext
#Binding var text: String
var note: Note
func makeUIView(context: Context) -> UITextView {
let textView = UITextView()
textView.delegate = context.coordinator
return textView
}
func updateUIView(_ textView: UITextView, context: Context) {
textView.text = text
}
func makeCoordinator() -> Coordinator {
Coordinator(self)
}
class Coordinator : NSObject, UITextViewDelegate {
var textView: BodyTextView
var saveQueued: Bool = false
init(_ textView: BodyTextView) {
self.textView = textView
}
func textViewDidChange(_ textView: UITextView) {
self.textView.text = textView.text
if (!saveQueued) {
saveQueued = true
Timer.scheduledTimer(withTimeInterval: 2, repeats: false) {_ in
print("saving from textViewDidChange: " + textView.text)
self.textView.note.body = textView.text
saveContext(self.textView.managedObjectContext)
self.saveQueued = false
}
}
}
}
}
This works well so far.
My problem is that if the view disappears before the 2 seconds is up it doesn't save the data. I'm guessing it is because when the view is dismissed it cancels the timer within the struct.
I'd like it to also save when the BodyTextView disappears as well.
Something like this:
func textViewDidDissapear(_ textView: UITextView) {
print("saving from textViewDidDissapear: " + textView.text)
self.textView.note.body = textView.text
saveContext(self.textView.managedObjectContext)
}
How do I do this?

Answer 1

The life cycle methods for SwiftUI.View's are a modifier on the view itself. so If you want to know when the view disappears add an .onDisappear() modifier to it.