Grouping Coredata by Date() in Swiftui List as Sections

Grouping CoreData by Date() in SwiftUI List as sections

You can make your own sectionIdentifier in your entity extension that works with @SectionedFetchRequest

The return variable just has to return something your range has in common for it to work.

extension Todo{
    ///Return the string representation of the relative date for the supported range (year, month, and day)
    ///The ranges include today, tomorrow, overdue, within 7 days, and future
    @objc
    var dueDateRelative: String{
        var result = ""
        if self.dueDate != nil{
            //Order matters here so you can avoid overlapping
            if Calendar.current.isDateInToday(self.dueDate!){
                result = "today"//You can localize here if you support it
            }else if Calendar.current.isDateInTomorrow(self.dueDate!){
                result = "tomorrow"//You can localize here if you support it
            }else if Calendar.current.dateComponents([.day], from: Date(), to: self.dueDate!).day ?? 8 <= 0{
                result = "overdue"//You can localize here if you support it
            }else if Calendar.current.dateComponents([.day], from: Date(), to: self.dueDate!).day ?? 8 <= 7{
                result = "within 7 days"//You can localize here if you support it
            }else{
                result = "future"//You can localize here if you support it
            }
        }else{
            result =  "unknown"//You can localize here if you support it
        }
        return result
    }
}

Then use it with your @SectionedFetchRequest like this

@SectionedFetchRequest(entity: Todo.entity(), sectionIdentifier: \.dueDateRelative, sortDescriptors: [NSSortDescriptor(keyPath: \Todo.dueDate, ascending: true)], predicate: nil, animation: Animation.linear)
var sections: SectionedFetchResults<String, Todo>

Look at this question too

You can use Date too but you have to pick a date to be the section header. In this scenario you can use the upperBound date of your range, just the date not the time because the time could create other sections if they don't match.

extension Todo{
    ///Return the upperboud date of the available range (year, month, and day)
    ///The ranges include today, tomorrow, overdue, within 7 days, and future
    @objc
    var upperBoundDueDate: Date{
        //The return value has to be identical for the sections to match
        //So instead of returning the available date you return a date with only year, month and day
        //We will comprare the result to today's components
        let todayComp = Calendar.current.dateComponents([.year,.month,.day], from: Date())
        var today = Calendar.current.date(from: todayComp) ?? Date()
        if self.dueDate != nil{
            //Use the methods available in calendar to identify the ranges
            //Today
            if Calendar.current.isDateInToday(self.dueDate!){
                //The result variable is already setup to today
                //result = result
            }else if Calendar.current.isDateInTomorrow(self.dueDate!){
                //Add one day to today
                today = Calendar.current.date(byAdding: .day, value: 1, to: today)!
            }else if Calendar.current.dateComponents([.day], from: today, to: self.dueDate!).day ?? 8 <= 0{
                //Reduce one day to today to return yesterday
                today = Calendar.current.date(byAdding: .day, value: -1, to: today)!
            }else if Calendar.current.dateComponents([.day], from: today, to: self.dueDate!).day ?? 8 <= 7{
                //Return the date in 7 days
                today = Calendar.current.date(byAdding: .day, value: 7, to: today)!
            }else{
                today = Date.distantFuture
            }
        }else{
            //This is something that needs to be handled. What do you want as the default if the date is nil
            today = Date.distantPast
        }
        return today
    }
}

And then the request will look like this...

@SectionedFetchRequest(entity: Todo.entity(), sectionIdentifier: \.upperBoundDueDate, sortDescriptors: [NSSortDescriptor(keyPath: \Todo.dueDate, ascending: true)], predicate: nil, animation: Animation.linear)
var sections: SectionedFetchResults<Date, Todo>

Based on the info you have provided you can test this code by pasting the extensions I have provided into a .swift file in your project and replacing your fetch request with the one you want to use

Grouping FechedResults by Month/Year to display a swiftui list with sections

You can sort the the fetched results if you use a different key in the temporary dictionary that can be properly sorted. So for the DateFormatter used in the function I set the format to "yyyy-MM" instead.

Note that I start by sorting the input to the function but this step is not needed if the fetched result is already sorted on date which I recommend.

func group(_ result : FetchedResults<LogEntry>) -> [[LogEntry]] {
    let sorted = result.sorted { $0.date < $1.date } 

    return Dictionary(grouping: sorted) { (element : LogEntry)  in
        dictionaryDateFormatter.string(from: element.date as Date)
    }.sorted { $0.key < $1.key }.map(\.value)
}

How to group core data items by date in SwiftUI?

I'm just getting into SwiftUI myself, so this might be a misunderstanding, but I think the issue is that the update function is unstable, in the sense that it does not guarantee to return the groups in the same order each time. SwiftUI consequently gets confused when new items are added. I found that the errors were avoided by specifically sorting the array:

func update(_ result : FetchedResults<Todo>)-> [[Todo]]{
    return  Dictionary(grouping: result){ (element : Todo)  in
        dateFormatter.string(from: element.date!)
    }.values.sorted() { $0[0].date! < $1[0].date! }
}

How to properly group a list fetched from CoreData by date?

You may try the following, It should work in your situation.

  @Environment(\.managedObjectContext) var moc
  @State private var date = Date()
  @FetchRequest(
    entity: Todo.entity(),
    sortDescriptors: [
      NSSortDescriptor(keyPath: \Todo.date, ascending: true)
    ]
  ) var todos: FetchedResults<Todo>

  var dateFormatter: DateFormatter {
    let formatter = DateFormatter()
    formatter.dateStyle = .short
    return formatter
  }

    func update(_ result : FetchedResults<Todo>)-> [[Todo]]{
      return  Dictionary(grouping: result){ (element : Todo)  in
            dateFormatter.string(from: element.date!)
      }.values.map{$0}
    }

  var body: some View {
    VStack {
      List {
        ForEach(update(todos), id: \.self) { (section: [Todo]) in
            Section(header: Text( self.dateFormatter.string(from: section[0].date!))) {
                ForEach(section, id: \.self) { todo in
            HStack {
            Text(todo.title ?? "")
            Text("\(todo.date ?? Date(), formatter: self.dateFormatter)")
            }
            }
          }
        }.id(todos.count)
      }
      Form {
        DatePicker(selection: $date, in: ...Date(), displayedComponents: .date) {
          Text("Datum")
        }
      }
      Button(action: {
        let newTodo = Todo(context: self.moc)
        newTodo.title = String(Int.random(in: 0 ..< 100))
        newTodo.date = self.date
        newTodo.id = UUID()
        try? self.moc.save()
      }, label: {
        Text("Add new todo")
      })
    }
  }

Deleting CoreData from SwiftUI List with Sections

This is how you would use the link...

Add this to the TodoRowView(todo: todo)

.swipeActions(content: {
    Button(role: .destructive, action: {
        deleteTodo(todo: todo)
    }, label: {
        Image(systemName: "trash")
    })
})

And you need this method in the View

public func deleteTodo(todo: Todo){
    viewContext.delete(todo)
    do{
        try viewContext.save()
    } catch{
        print(error)
    }
}

Or you can use your current setup that uses onDelete on the ForEach

.onDelete { indexSet in
    deleteTodo(section: Array(section), offsets: indexSet)
    }

That uses this method

func deleteTodo(section: [Todo], offsets: IndexSet) {
    for index in offsets {
        let todo = section[index]
        viewContext.delete(todo)
    }
    try? viewContext.save()
}

And of course for any of this to work you need a working

@Environment(\.managedObjectContext) var viewContext

At the top of your file

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