edit a Core Data Object in SwiftUI - core-data

Question

I push an object that comes from the Core Data Database to a detail page with text fields.
When the user changes the text in the textfields and presses save the changes should be saved to the core data DB.
Problem: I have no clue how to modify/update/change an existing core data entity.
I probably need to get the original via a #FetchRequest but every time I try I get some problems.
Question 1: Let's say the entity has object.id as UUID, how can I
fetch that object in SwiftUI?
Question 2: How can I overwrite the fetched object with the changed
content of the textfields?
struct ProductDetail: View {
#State var barcode: Barcode
#Environment(\.presentationMode) var presentationMode
#Environment(\.managedObjectContext) var context
//let datahandler = Datahandler()
var body: some View {
VStack {
HStack {
Text("Barcode: ")
Spacer()
TextField("Barcode", text: Binding($barcode.code, ""))
.textFieldStyle(RoundedBorderTextFieldStyle())
.frame(width: 250, alignment: .trailing)
}
HStack {
Text("Amount: ")
Spacer()
TextField("Amount", text: Binding($barcode.amount, ""))
.textFieldStyle(RoundedBorderTextFieldStyle())
.frame(width: 250, alignment: .trailing)
.keyboardType(.numberPad)
}
HStack{
Button("Back") {
self.presentationMode.wrappedValue.dismiss()
}
Spacer()
Button("Save"){
//self.datahandler.updateBarcode(barcode: self.object)
self.editBarcode(barcode: barcode)
self.presentationMode.wrappedValue.dismiss()
}
}
.padding()
}
.padding()
}
func editBarcode(barcode: Barcode) {
// Question 1: Fetch Original object using barcode.id
// Question 2: How to but barcode into context so it can overwrite the core data original?
try? context.save()
}
Attempt:
func editBarcode(barcode: Barcode) {
#FetchRequest(sortDescriptors: [], predicate: NSPredicate(format: "self.id IN %#", barcode.id)) var results: FetchedResults<Barcode>
results.first?.amount = barcode.amount
results.first?.code = barcode.code
try? context.save()
}
Errors:
Argument type 'UUID?' does not conform to expected type 'CVarArg'
Cannot use instance member 'barcode' within property initializer;
property initializers run before 'self' is available
Property wrappers are not yet supported on local properties