Firebase dispatch_async keeps crashing -swift 2 iOS9 - ios

Question

I'm using a tabBar Controller. TabOne is the rootVC. In TabOne I have a viewController that is sending info to Firebase via a sendButton and programmatically presenting TabTwo.
In TabTwo I have tableView controller that gets the info and displays it. Oddly twice I ran the code and everything was fine, I pressed the sendButton, TabTwo gets presented, it's tableview correctly loads the cells with the correct info. The problem is now for some strange reason it only successfully ran those 2 times and it has been crashing on dispatch_async ever since.
Now I just tried to run the simulator and instead of pressing the sendButton in TabOne I pressed the tab for TabTwo and the app crashes on dispatch_async. I didn't attempt to send anything to Firebase, I just clicked the tab for TabTwo and dispatch_async crashed with code:
Thread1: EXC_BAD_INSTRUCTION (code=EXC_1338_INVOP, subcode=0x0)
Any idea why it seems to crash when I switch tabs?
Any idea why everything ran fine twice then all of a sudden crash?
Here is the code:
ModelObject
class CookieModel: NSObject{
var name: String?
}
tab1
class TabOneController: UIViewController{
var dbRef: FIRDatabaseReference!
let userID: String? = (FIRAuth.auth()?.currentUser?.uid)!
let cookieModel = [CookieModel]()
override func viewDidLoad() {
super.viewDidLoad()
self.dbRef = FIRDatabase.database().reference()
}
#IBAction func sendButton(sender: UIButton){
self.sendToFireBase()
let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
let tabBarController = mainStoryboard.instantiateInitialViewController() as! UITabBarController
tabBarController.selectedIndex = 1
self.presentViewController(tabBarController , animated: true, completion: nil)
}
//Code to send data to FirebaseDatabase
func sendToFireBase(){
let uniquePath = NSUUID().UUIDString
let usersIDRef = self.dbRef.child("users").child(self.userID!)
let cookiePath = usersIDRef.child("cookieData").child(self.uniquePath)
let cookie0 = CookieModel()
cookie0.name = "oatmeal"
self.cookieModel.append(cookie0)
let cookie1 = CookieModel()
cookie1.name = "chocolate"
self.cookieModel.append(cookie1)
let cookie2 = CookieModel()
cookie2.name = "coconut"
self.cookieModel.append(cookie2)
var cookieDict = [String:AnyObject]()
cookieDict.updateValue(cookie0.name!, forKey: "cookie0")
cookieDict.updateValue(cookie1.name!, forKey: "cookie1")
cookieDict.updateValue(cookie2.name!, forKey: "cookie2")
cookiePath.updateChildValues(cookieDict, withCompletionBlock: {
(error, user) in
if error != nil{
print((error?.localizedDescription))
return
}
}
}
tab2
class TabTwoController: UIViewController, UITableViewDataSource, UITableViewDelegate{
#IBOutlet weak var tableView: UITableView!
var dbRef: FIRDatabaseReference!
let userID: String? = (FIRAuth.auth()?.currentUser?.uid)!
var cookieModel = [CookieModel]()
override func viewDidLoad() {
super.viewDidLoad()
self.dbRef = FIRDatabase.database().reference()
self.tableView.delegate = self
self.observeFBCookieData()
}
//Code to retrieve data from FirebaseDatabase
func observeFBCookieData(){
let usersIDRef = self.dbRef.child("users").child(self.userID!)
let cookiePath = usersIDRef.child("cookieData")
cookiePath.observeEventType(.ChildAdded, withBlock: {
(snapshot) in
if let dict = snapshot.value as? [String:AnyObject]{
let cookie0 = dict["cookie0"] as? String
let cookie1 = dict["cookie1"] as? String
let cookie2 = dict["cookie2"] as? String
let cookie0 = CookieModel()
cookie0.name = cookie0!
self.cookieModel.append(cookie0)
let cookie1 = CookieModel()
cookie1.name = cookie1!
self.cookieModel.append(cookie1)
let cookie2 = CookieModel()
cookie2.name = cookie2!
self.cookieModel.append(cookie2)
dispatch_async(dispatch_get_main_queue(), {
self.tableView.reloadData()
})
}
}, withCancelBlock: nil)
}
//MARK: -TableViewDatasource Methods
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return self.cookieModel.count
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath) as! MyCookieCell
cell.titleLabel.text = self.cookieModel[IndexPath.row].name!
return cell
}
}

Answer 1

Try setting the table view's data source in your viewDidLoad after setting its delegate.
Self.tableView.datasource = self