Realm Array and child relationships - swift

Question

I am trying to make a List in relation to my realm array. I don't know if it is possible to take a hard coded realm array and give each string its own list. Currently I have my array in a table view and when a row is selected it segues to its own viewController. I am trying to get each selected row to contain its own list. Here's the code
Data Model 1
import Foundation
import RealmSwift
class DateChange: Object {
#objc dynamic var itemId : String = UUID().uuidString
override static func primaryKey() -> String? {
return "itemId"
}
let dates = List<String>()
let selection = List<Home>()
convenience init(tag: String) {
self.init()
}
}
Data Model 2
class Home: Object {
#objc dynamic var itemId : String = UUID().uuidString
override static func primaryKey() -> String? {
return "itemId"
}
var parentCategory = LinkingObjects(fromType: Home.self, property: "selection")
View Controller 1
class WeekOfViewController: NSViewController {
let post = DateChange(tag: "")
post.dates.append("December 30th - January 5th")
post.dates.append("January 13th - January 19th")
}
func numberOfRows(in tableView: NSTableView) -> Int {
return 2
}
func tableView(_ tableView: NSTableView, viewFor tableColumn: NSTableColumn?, row: Int) -> NSView? {
let cell = tableView.makeView(withIdentifier:
NSUserInterfaceItemIdentifier(rawValue: "dateCell") , owner: self) as! NSTableCellView?
cell?.textField?.stringValue = post.dates[row]
return cell
}
func tableViewSelectionDidChange(_ notification: Notification) {
self.performSegue(withIdentifier: "selectedDate", sender: self)
}
override func prepare(for segue: NSStoryboardSegue, sender: Any?) {
// Unwrap the segue's identifier.
guard let identifier = segue.identifier else { return }
// Make sure this is the segue we care about.
if identifier == "selectedDate" {
let secondVC = segue.destinationController as! ViewController2
// Figure out which row was selected.
if let selectedRow = dateTableView?.selectedRow {
secondVC.selectedDate = post.dates[selectedRow]
}
View Controller 2
class ViewController2: NSViewController {
#IBAction func saveData(_ sender: NSButton) {
if let appendDate = selectedDate {
do {
try realm?.write {
let homeData = Home()
homeData.done = false
appendDate.dates.append()
}
} catch {
print("There was an error saving")
}
}
}

Answer 1

Yes. You can make multiple dimensional arrays.
Example:
1. Year object has a list of months
2. Month object has a list of days
3. Day object has a list of hours
4. etc, etc
When you app launches, you create a loop which initializes a Year, then initializes lots of months and appends them into the Year.Month_Array. Do the same for days_array in each month.
To save in Realm, call:
try! realm.write {
realm.add(Year)
}
Now you can read out you multi-level Realm object anytime you wish.
If my answer isn't clear, please let me know

Answer 2

The exact use case is a bit unclear but it seems that the app is a Master->Detail configuration where the master page contains a list of dates and then when a date is tapped, it segues to a detail page with further info.
Here's an example of code to handle the objects. You know how to populate a tableView with it's delegate methods so I'm omitting that part.
Suppose we want a list of events on the master page and then the activities of each event on the detail page. Start with two managed Realm objects; the event object which has a start and end date, the event title and the activities list within that event. Then there's the activity object.
class EventClass: Object {
#objc dynamic var start_date: Date?
#objc dynamic var end_date: Date?
#objc dynamic var event_title = ""
let activities = List<ActivityClass>()
}
class ActivityClass: Object {
#objc dynamic var title = ""
}
write an event with some activities to Realm
let formatter = DateFormatter()
formatter.dateFormat = "yyyymmdd"
let e0 = EventClass()
e0.event_title = "Workshop"
e0.start_date = formatter.date(from: "20180113")
e0.end_date = formatter.date(from: "20180119")
let a0e0 = ActivityClass()
a0e0.title = "Some activity"
let a0e1 = ActivityClass()
a0e1.title = "Another activity"
let a0e2 = ActivityClass()
a0e2.title = "Activity continues"
e0.activities.append(a0e0)
e0.activities.append(a0e1)
e0.activities.append(a0e2)
// write event 0 (e0) to realm which will create the event and activities
We are assuming both the master and detail views have tableViews, so load the events into the master tableView dataSource which is a Realm results class - it behaves like an array.
class ViewController: NSViewController {
var eventResults: Results<EventClass>? = nil
and then whenever it's time to populate the dataSource:
self.eventResults = realm.objects(EventClass.self)
and then the tableView delegate methods can get each row for display. It would look something like this on the master page
func tableView(_ tableView: NSTableView, viewFor tableColumn: NSTableColumn?, row: Int) -> NSView? {
let cell = tableView.makeView(withIdentifier:
NSUserInterfaceItemIdentifier(rawValue: "dateCell") , owner: self) as! NSTableCellView?
//cell?.textField?.stringValue = post.dates[row]
let event = self.eventResults[row]
cell.textField?.stringValue = "Event: \(title) from: \(start) - \(end)"
return cell
}
so then the tableView would look something like this
Event: Workshop from: 2018-12-30 - 2018-01-05
Event: Workshop from: 2018-01-13 - 2018-01-19
etc
when a row is tapped, get that event object from the master tableView datasource, self.eventResults
let tappedEvent = self.eventResults[tappedRowIndex]
and then get the activity list
let activityList = tappedEvent.activities
that activityList can be passed via the segue (or 1000 other ways) to the detail viewController and it becomes the dataSource for the detail tableView. The detail page follows the same pattern except the dataSource is the activities.
Does that help?