How can I save event array into iCalendar

I've some code for insert event

     for event in events {
                for ct in 0..<self.holidayArray!.count {
                    if self.dateFormatter2.string(from: event.startDate) == self.holidayArray?[ct].start?.date && event.title == self.holidayArray?[ct].summary {
                        print("\(event.title)")
                        clue = "same data with iCal"
                        //skip data
                    } else { //save data into iCal
                        let startDate = self.holidayArray?[ct].start?.date
                        let endDate = self.holidayArray?[ct].end?.date
                        event.title = self.holidayArray?[ct].summary
                        event.startDate = self.dateFormatter2.date(from: startDate!)
                        print(self.dateFormatter2.date(from: startDate!))
                        event.endDate = self.dateFormatter2.date(from: endDate!)
                        print(self.dateFormatter2.date(from: endDate!))
                        print(event.notes)
                        event.calendar = store.defaultCalendarForNewEvents
                        
                        do {
                            print("\nTITLE = \(event.title)")
                            try self.eventStore.save(event, span: .thisEvent)
                            print("Saved Event\n")
                        } catch let error as NSError {
                            print("failed to save event with error : \(error)")
                        }
                    }
                }
            }

when the code running, sometimes data that i want to save goes into error with details EKErrorDomain Code=11 EKErrorObjectBelongsToDifferentStore and some data that can be saved is having repeating name. Here's the screenshot that having problem [1]: https://i.stack.imgur.com/TtrIf.png [2]: https://i.stack.imgur.com/yIiyQ.png

How can i fix it? Thank you.