Default value for UITableView Cell if Firebase snapshot is nil - swift

Question

I have looked around and I cannot figure this out.
I am trying to set a default value of a tableView Cell if a Firebase snapshot returns nil
Example:
A snapshot is made to show all the event names from my Firebase Database
in a tableView using a dequeReusableCell.
But if the snapshot returns nil, the tableView returns with 1 cell with a label saying "Sorry, there are no events."
Here is my firebase snapshot code. This code does currently handle if the snapshot does return nil with a print() statement.
func populateTableView(){
let uid = Auth.auth().currentUser?.uid
ref = Database.database().reference()
ref.child("events").child(uid!).child(currentDate).observeSingleEvent(of: .value, with: { (snapshot) in
self.events = []
if let snapshot = snapshot.children.allObjects as? [DataSnapshot] {
for snap in snapshot {
//print("SNAP: \(snap)")
if let postDict = snap.value as? Dictionary<String, AnyObject> {
let key = snap.key
let event = Event(postKey: key, postData: postDict)
self.events.append(event)
//print(self.events)
}
}
}
if !snapshot.exists() {
self.eventStatus = false
self.tableView.reloadData()
print("No Event here")
} else {
self.eventStatus = true
self.tableView.reloadData()
}
})
}
The firebase Objects get stored into the Event class and are stored a dictionary. I don't think this code is needed, but here is the event class code for more context.
import Foundation
import Firebase
class Event {
var ref: DatabaseReference!
private var _description: String!
private var _imageUrl: String!
private var _eventTitle: String!
private var _eventType: String!
private var _eventTime: String!
private var _eventStartDate: String!
private var _eventEndDate: String!
private var _monthlyRepeat: String!
private var _weeklyRepeat: String!
private var _eventColor: String!
private var _postKey: String!
private var _postRef: DatabaseReference!
var description: String {
return _description
}
var imageUrl: String {
return _imageUrl
}
var eventTitle: String {
return _eventTitle
}
var eventType: String {
return _eventType
}
var eventTime: String {
return _eventTime
}
var eventStartDate: String {
return _eventStartDate
}
var eventEndDate: String {
return _eventEndDate
}
var monthlyRepeat: String {
return _monthlyRepeat
}
var weeklyRepeat: String {
return _weeklyRepeat
}
var eventColor: String {
return _eventColor
}
var postKey: String {
return _postKey
}
init(postKey: String, postData: Dictionary<String, AnyObject>) {
self._postKey = postKey
if let description = postData["description"] as? String {
self._description = description
}
if let imageUrl = postData["event_Image_URL"] as? String {
self._imageUrl = imageUrl
}
if let eventTitle = postData["event_Title"] as? String {
self._eventTitle = eventTitle
}
if let eventType = postData["event_Type"] as? String {
self._eventType = eventType
}
if let eventTime = postData["event_Time"] as? String {
self._eventTime = eventTime
}
if let eventStartDate = postData["start_Date"] as? String {
self._eventStartDate = eventStartDate
}
if let eventEndDate = postData["end_Date"] as? String {
self._eventEndDate = eventEndDate
}
if let monthlyRepeat = postData["monthly_Repeat"] as? String {
self._monthlyRepeat = monthlyRepeat
}
if let weeklyRepeat = postData["weekly_Repeat"] as? String {
self._weeklyRepeat = weeklyRepeat
}
if let eventColor = postData["color"] as? String {
self._eventColor = eventColor
}
let uid = Auth.auth().currentUser?.uid
ref = Database.database().reference()
let eventRef = ref.child("events").child(uid!).child("Monday May, 29")
_postRef = eventRef.child(_postKey)
}
}

Answer 1

The simplest way to solve this is to add a title UILabel to your ViewcController and change the text when snapshot is not available.
Or if that doesn't work for you for some reason you could try this:
I did not check this, but I might get you on track.
First you will need to change your populateTableView method so that an events array is created even when snapshot has no results. This way the events array count will be 1 (and one row will be added to your tableView) even if snapshot had no result.
populateTableView(){
let uid = Auth.auth().currentUser?.uid
ref = Database.database().reference()
ref.child("events").child(uid!).child(currentDate).observeSingleEvent(of: .value, with: { (snapshot) in
self.events = []
if let snapshot = snapshot.children.allObjects as? [DataSnapshot] {
for snap in snapshot {
//print("SNAP: \(snap)")
if let postDict = snap.value as? Dictionary<String, AnyObject> {
let key = snap.key
let event = Event(postKey: key, postData: postDict)
self.events.append(event)
//print(self.events)
}
}
}
else{ // Snapshot does not exist
let postDict: Dictionary<String, AnyObject> // Add an empty Dictionary
let key = -1 // Or what ever value you could not possibly expect
let event = Event(postKey: key, postData: postDict)
self.events.append(event)
self.tableView.reloadData()
print("No Event here")
}
})
}
Notice that when snapshot is not valid or available you add an empty Dictionary with an unique key value to your events array.
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return events.count
}
You need to create two custom cells with unique identifiers.
Now you can "actually" populate your tableView similar to this:
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let event = events.[indexPath.row]
let conditionKey = event.key
if(conditionKey == -1){ // or whatever value you gave in populateTableView to indicate that snapshot did not exist
let cell = tableView.dequeueReusableCell(withIdentifier: "identifierCellNotSoGood", for: indexPath) as! CustomCellNotSoGood
cell.noSnapShotLabel1.text = "Sorry, there are no events."
return cell
}
else{
let cell = tableView.dequeueReusableCell(withIdentifier: "identifierCellAllGood", for: indexPath) as! CustomCellAllGood
cell.yourCustomLabel1.text = event.key // Or whatever data you are displaying
cell.sourCustomLabel2.text = event.event // Or whatever data you are displaying
return cell
}
return UITableViewCell
}
If you need to handle the selection of a table cell you can do this:
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
// get rid of the ugly highlighting
tableView.deselectRow(at: indexPath, animated: false)
let event = events.[indexPath.row
let conditionKey = event.key
if(conditionKey == -1){ // or whatever value you gave in populateTableView to indicate that snapshot did not exist
// Do what you need or not
}
else{
// Do something meaningful with your database
doSomething(withEventData: event)
}
}