Reloading a TableView after changes to a Realm database - ios

Question

I'm building a project management app in Swift using Realm as a database to store my projects.
ThisWeekViewController is my initial View Controller; it incorporates a UITableView to show projects that are due this week. Using a Bar Button, the user can segue to AddProjectViewController, which, as the name suggests, is used to create new projects and save them to the realm database. AddProjectViewController is presented modally.
After entering the required project details, the user can click a save button, which saves the project to the realm database and dismisses the view, returning to ThisWeekViewController. However, I'm having trouble updating the TableView to reflect the addition of a new project.
After consulting the Realm documentation, I now understand that in Realm, it is not necessary to manually add or delete rows from my TableView after the database has changed. Instead, you should use a notification handler. However, I'm not quite sure how and where to incorporate it in order to reload my TableView after dismissing AddProjectViewController.
Calling the handler in ThisWeekViewController's ViewWillAppear method won't work as the view never actually disappears, because AddProjectViewController is presented modally.
AddProjectViewController:
class AddProjectViewController: FormViewController {
// Realm Initialization
let realm = try! Realm()
override func viewDidLoad() {
super.viewDidLoad()
self.navigationItem.rightBarButtonItem?.isEnabled = false
form +++ Section()
<<< TextRow(){ row in
row.placeholder = "Postname"
row.tag = "ProjectName"
}.onChange({ (row) in
if row.cell.textField.hasText {
self.navigationItem.rightBarButtonItem?.isEnabled = true
} else {
self.navigationItem.rightBarButtonItem?.isEnabled = false
}
})
<<< TextAreaRow() { row in
row.placeholder = "Notizen"
row.textAreaHeight = .fixed(cellHeight: 240.0)
row.tag = "ProjectNotes"
}
form +++ Section()
<<< DateTimeInlineRow() { row in
row.title = "Fällig am"
row.value = Date(timeIntervalSinceNow: 0)
row.minuteInterval = 15
row.tag = "ProjectDueDate"
}
navigationOptions = RowNavigationOptions.Enabled.union(.StopDisabledRow)
animateScroll = true
rowKeyboardSpacing = 20
}
// MARK: - User defined functions
// If user presses the cancel button, the view is dismissed from screen.
#IBAction func cancelButtonPressed(_ sender: UIBarButtonItem) {
dismiss(animated: true) {}
}
// If user presses the save button, a new Project() item is created and saved to the Realm database.
#IBAction func saveButtonPressed(_ sender: UIBarButtonItem) {
// print(form.values())
let newProject = Project()
let titleRow: TextRow? = form.rowBy(tag: "ProjectName")
let projectName = titleRow?.value
newProject.title = projectName!
let notesRow: TextAreaRow? = form.rowBy(tag: "ProjectNotes")
let projectNotes = notesRow?.value
newProject.notes = projectNotes
let dueDateRow: DateTimeInlineRow? = form.rowBy(tag: "ProjectDueDate")
let projectDueDate = dueDateRow?.value
newProject.dueDate = projectDueDate
newProject.dateCreated = NSDate.now
print(newProject)
// Save the new Project to the realm database
do {
try self.realm.write {
realm.add(newProject)
}
}
catch {
print("Error saving item to Realm database. \(error)")
}
print(newProject)
self.dismiss(animated: true)
}
}
ThisWeekViewController:
class ThisWeekViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
// MARK: - Variables
#IBOutlet weak var thisWeekTableView: UITableView!
// Realm initialization
let realm = try! Realm()
override func viewDidLoad() {
super.viewDidLoad()
setupTableView()
print(Realm.Configuration.defaultConfiguration.fileURL!)
}
// MARK: - Data Source / Delegate Methods
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 7
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
//TODO: Handle user selection of a specific planned post
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
// Variables
let thisWeekCell = thisWeekTableView.dequeueReusableCell(withIdentifier: ThisWeekTableViewCell.reuseIdentifier()) as! ThisWeekTableViewCell
let today = Date()
let day = Calendar.current.date(byAdding: .day, value: indexPath.row, to: today)
let dayNumber = Calendar.current.component(.day, from: day!)
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "EEEE"
let dayName = dateFormatter.string(from: day!)
let startOfToday = Calendar.current.startOfDay(for: day!)
let endOfToday = Calendar.current.date(byAdding: .second, value: 86399, to: startOfToday)!
let projectNamesForCurrentDay = projectNamesForDay(startOfDay: startOfToday, endOfDay: endOfToday)
thisWeekCell.setupProjectNameLabel(projectNames: projectNamesForCurrentDay)
if indexPath.row == 0 {
thisWeekCell.dayNumberLabel.textColor = UIColor.orange
thisWeekCell.dayTextLabel.text = "Heute (\(dayName))"
}
if indexPath.row == 1 {
thisWeekCell.dayTextLabel.text = "Morgen (\(dayName))"
}
if indexPath.row > 1 {
thisWeekCell.dayTextLabel.text = dayName
}
thisWeekCell.dayNumberLabel.text = String(dayNumber)
return thisWeekCell
}
// MARK: - User definded functions
/**
Initial setup for the TableView. Registers all neccessary custom cells, sets the delegate and dataSource, and enables AutoLayout.
*/
func setupTableView() {
thisWeekTableView.register(UINib(nibName: ThisWeekTableViewCell.nibName(), bundle: nil), forCellReuseIdentifier: ThisWeekTableViewCell.reuseIdentifier())
thisWeekTableView.delegate = self
thisWeekTableView.dataSource = self
thisWeekTableView.rowHeight = UITableView.automaticDimension
thisWeekTableView.estimatedRowHeight = 54.0
}
/**
Takes two boundary objects of type Date and returns an array of strings containing the titles of all projects in the database that have a due date between the boundary dates.
- Parameter startOfDay: The start-of-day boundary object
- Parameter endOfDay: The end-of-day boundary object
- Returns: An array of strings containing project titles
*/
func projectNamesForDay(startOfDay: Date, endOfDay: Date) -> [String] {
let filteredProjects = realm.objects(Project.self).filter("dueDate BETWEEN %#", [startOfDay, endOfDay])
var projectNames = [String]()
for project in filteredProjects {
projectNames.append(project.title)
}
return projectNames
}
}

Answer 1

You should use Realm notification to auto update tableview each time Project Result change:
// Observe Realm Notifications
let token = projectResult.observe { notification, realm in
// reloadTableView
}
// later
token.invalidate()