Don't Display Entry Date if Same as previous Entry Date in List - swiftui

Question

I have a list of entries containing dates. I would like to only display the date if it is different from the previous entry date.
I am reading in the entries from core data and passing them to the method ckEntryDate for determination of whether to display the date. The method is called from inside a list. If the string returned by ckEntryDate is blank (string.isEmpty) I know that the current entry date is the same as the previous date and I don't need to display the date.
There are no errors occurring, but the current entry date is not being saved via userDefaults. I would appreciate any ideas on how to save the current date or how to check for identical dates.
Thanks
struct HistoryView: View {
#EnvironmentObject var userData: UserData
#Environment(\.managedObjectContext) var viewContext
// fetch core data
#FetchRequest(
entity: CurrTrans.entity(),
sortDescriptors: [NSSortDescriptor(keyPath: \CurrTrans.entryDT, ascending: true)]
) var currTrans: FetchedResults<CurrTrans>
var body: some View {
GeometryReader { g in
VStack (alignment: .leading) {
ShowTitle(g:g, title: "History")
ShowHistoryHeader(g: g)
ScrollView (.vertical) {
List {
ForEach(currTrans, id: \.id) { item in
let entryDate = userData.ckEntryDate( item: item)
showRow(g:g, item: item, entryDate: entryDate)
}
.onDelete(perform: deleteItem)
}
}.font(.body)
}
}
}
This method is part of the class UserData: ObservableObject {
// check if history entry date is same as previous date or the first entry
func ckEntryDate( item: CurrTrans) -> (String) {
var outDate: String = ""
var savedDate: String = ""
//read in savedDate
if UserDefaults.standard.string(forKey: "storeDate") != "" {
savedDate = UserDefaults.standard.string(forKey: "storeDate") ?? ""
}else {
savedDate = ""
}
// convert Date? to String
let cdate = item.entryDT ?? Date()
let currDate = cdate.getFormattedDate()
// check if no previous entries
if savedDate.isEmpty {
outDate = currDate
}
else { // savedDate is not blank
if savedDate == currDate {
outDate = ""
}
else { // date entries different
outDate = currDate
}
savedDate = currDate
}
// save savedDate
UserDefaults.standard.set(savedDate, forKey: "saveDate")
return outDate
}
}
extension Date {
func getFormattedDate() -> String {
// localized date & time formatting
let dateformat = DateFormatter()
dateformat.dateStyle = .medium
dateformat.timeStyle = .none
return dateformat.string(from: self)
}
}

Answer 1

Assuming your function ckEntryDate works correctly, you could try this approach of filtering the data at the ForEach:
ForEach(currTrans.filter { "" != userData.ckEntryDate(item: $0) }, id: \.id) { item in
showRow(g:g, item: item, entryDate: userData.ckEntryDate(item: item))
}
You can also try this:
ForEach(currTrans, id: \.id) { item in
let entryDate = userData.ckEntryDate(item: item)
if !entryDate.isEmpty {
showRow(g:g, item: item, entryDate: entryDate)
}
}

Answer 2

I have been looking for a way to persist the current entry date for comparison to the next entry date for checking if the dates are the same.
I discovered that I could do this by simply placing a variable at the top of the class that contains the method ckEntryDate.
class UserData: ObservableObject {
var storedDate: String = ""
So thanks to all who took the time to consider a possible answers.
// check if history entry date is the 1st entry or the same as previous date
func ckEntryDate( item: CurrTrans) -> (String) {
var outDate: String = ""
// initialzie the entry date
let cdate = item.entryDT ?? Date()
let entryDate = cdate.getFormattedDate()
// if savedDate is blank -> no previous entries
if storedDate.isEmpty {
outDate = entryDate
}
else { // savedDate is not blank
if storedDate == entryDate {
outDate = ""
}
else { // date entries different
outDate = entryDate
}
}
storedDate = entryDate
// outDate returns blank or the current date
return (outDate)
}
}