leaky listener firebase ios - ios

Question

I am trying to load message box data for chat functionality.
The message box is loaded as:
override func viewDidAppear(animated: Bool) {
super.viewDidAppear(animated)
if (PFUser.currentUser()!["firebaseUID"] !== nil)
{
print(PFUser.currentUser()!["firebaseUID"])
self.updateResultArray(PFUser.currentUser()!["firebaseUID"] as! String)
}
}
func updateResultArray(uid: String) {
let userName = String(PFUser.currentUser()!["username"])
//print("updateResultArray is getting called")
let userhandle = self.firebase.childByAppendingPath("users").childByAppendingPath(uid).childByAppendingPath("rooms").queryOrderedByValue()
.observeSingleEventOfType(.Value, withBlock: { roomsnapshot in
let enumerator = roomsnapshot.children
while let rest = enumerator.nextObject() as? FDataSnapshot {
self.roomArray.append(rest.key)
}
//get the latest message from all the rooms
if self.roomArray.isEmpty == false
{
for i in 0...self.roomArray.count-1
{
print("in the room loop \(self.roomArray[i])")
let messagehandle = self.messagesRef.childByAppendingPath(self.roomArray[i]).queryOrderedByKey().queryLimitedToFirst(1).observeSingleEventOfType(.Value, withBlock: {
messagesnapshot in
print("the messagesnapshot child count is \(messagesnapshot.childrenCount)")
let enumerator = messagesnapshot.children
while let rest = enumerator.nextObject() as? FDataSnapshot {
let sender = rest.value.objectForKey("sender") as? String
let reciever = rest.value.objectForKey("reciever") as? String
//print("sender is \(sender!) and reciever is \(reciever!)")
let eventhandle = self.firebase.childByAppendingPath("rooms").childByAppendingPath(self.roomArray[i]).observeSingleEventOfType(.Value, withBlock: { eventsnapshot in
if eventsnapshot.value is NSNull {
// The value is null
}
else
{
let eventAttr = eventsnapshot.value.objectForKey("eventAttributes") as? String
let eventDetails = eventsnapshot.value.objectForKey("eventDetails") as? String
//print("userName is \(userName)")
//print("sender is \(sender)")
if (userName != sender!) //for event joinee
{
let firstname1 = eventsnapshot.value.objectForKey("firstname1") as? String
self.otherNames.append(sender!)
self.resultsNameArray.append(firstname1!)
self.base4String = eventsnapshot.value.objectForKey("img1") as! String
self.resultsImageFiles.append(self.base4String)
}
else //for event creator
{
let firstname2 = eventsnapshot.value.objectForKey("firstname2") as? String
self.otherNames.append(reciever!)
self.resultsNameArray.append(firstname2!)
self.base4String = eventsnapshot.value.objectForKey("img2") as! String
self.resultsImageFiles.append(self.base4String)
}
let newlineChars = NSCharacterSet.newlineCharacterSet()
let evntArray = eventDetails!.componentsSeparatedByCharactersInSet(newlineChars).filter{!$0.isEmpty}
self.eventArray.append(evntArray[0])
self.eventdetailsArray.append(eventAttr!)
dispatch_async(dispatch_get_main_queue()) { () -> Void in
self.resultsTable.reloadData()
}
}
})
// self.firebase.removeAuthEventObserverWithHandle(eventhandle)
}
})
//self.messagesRef.removeAuthEventObserverWithHandle(messagehandle)
}
}
})
//firebase.removeAuthEventObserverWithHandle(userhandle)
}
since i am using observeSingleEventOfType i havent coded to remove handlers( i have tried that as well).
In the individual chat, the code is like this:
func refreshResults() {
print("the roomid is \(roomid)")
//update from firebase
let messagehandle = self.messagesRef.childByAppendingPath(roomid).queryOrderedByKey()
.observeEventType(.Value, withBlock: { messageTextsnapshot in
self.messageArray.removeAll()
self.senderArray.removeAll()
// print("the messageTextsnapshot child count is \(messageTextsnapshot.childrenCount)") // I got the expected number of items
let enumerator = messageTextsnapshot.children
while let rest = enumerator.nextObject() as? FDataSnapshot {
let text = rest.value.objectForKey("message") as? String
let sender = rest.value.objectForKey("sender") as? String
if text != nil && text != ""
{
self.messageArray.append(text!)
self.senderArray.append(sender!)
}
}
for subView in self.resultsScrollView.subviews {
subView.removeFromSuperview()
}
for var i = 0; i <= self.messageArray.count-1; i++ {
if self.senderArray[i] == userName {
if (self.messageArray[i].rangeOfString(self.acceptMessage) != nil)
{
let chatBubbleData = ChatBubbleData(text: self.messageArray[i], image:self.myImg, date: NSDate(), type: .AcceptMine)
self.addChatBubble(chatBubbleData)
}
else
{
let chatBubbleData = ChatBubbleData(text: self.messageArray[i], image:self.myImg, date: NSDate(), type: .Mine)
self.addChatBubble(chatBubbleData)
}
} else {
if (self.messageArray[i].rangeOfString(self.acceptMessage) != nil)
{
let chatBubbleData = ChatBubbleData(text: self.messageArray[i], image:self.otherImg, date: NSDate(), type: .Accept)
self.addChatBubble(chatBubbleData)
}
else
{
let chatBubbleData = ChatBubbleData(text: self.messageArray[i], image:self.otherImg, date: NSDate(), type: .Opponent)
self.addChatBubble(chatBubbleData)
}
}
let bottomOffset:CGPoint = CGPointMake(0, self.resultsScrollView.contentSize.height - self.resultsScrollView.bounds.size.height)
self.resultsScrollView.setContentOffset(bottomOffset, animated: false)
}
})
self.messagesRef.removeAuthEventObserverWithHandle(messagehandle)
}
There are a few other listeners similar to this. the problem is when i go back from this view(individual chat to message box, the memory consumption increases. I have cleared all arrays and closed the handlers immediately after use. but still memory consumption increases and sometimes in message box same rows are replicated again. how should i solve this. I tried using
observeSingleEventOfType but it is not a correct solution as the data sync stops.
Used this as reference:
https://www.firebase.com/blog/2015-10-15-best-practices-uiviewcontroller-ios-firebase.html

Answer 1

It looks like your message box object is not being released due to a retain cycle caused by the listener callback block holding a reference to the message box object. You can alleviate this by using [weak self] in blocks that you pass to other objects. For example:
.observeSingleEventOfType(.Value, withBlock:
{
[weak self] roomsnapshot in
let enumerator = roomsnapshot.children
...
This makes 'self' an optional type, and you can then add:
guard let strongSelf = self else { ... }

Answer 2

The problem was that i was closing the listeners on the parent and not on the child. so the listeners were still in memory.
When i closed the listeners on the full path it worked.