Firebase

Conversation.swift

FIRDatabase.database().reference().child("conversations").child(location).observe(.value, with: { (snapshot) in
    
    if(snapshot.childrenCount > 1) {
        var removeCount = Int(snapshot.childrenCount) - 1
        let enumerator = snapshot.children
        
        while let rest = enumerator.nextObject() as? FIRDataSnapshot {
            rest.ref.removeValue()
            removeCount -= 1
            if(removeCount == 0) {
                break
            }
        }
    }
    
    completion(true)
    
}, withCancel: { (error) in
    print(error)
})

Message.swift

//Downloads messages
func fetchData() {
    
    Message.downloadAllMessages(forUserID: self.currentUser!.id, completion: {[weak weakSelf = self] (message) in

        weakSelf?.items.removeAll()
        weakSelf?.items.append(message)
        weakSelf?.items.sort{ $0.timestamp < $1.timestamp }

        if let itemsCount = weakSelf?.items.count {
            if(itemsCount > 1) {
                let range = 1..<itemsCount
                weakSelf?.items.removeSubrange(range)
                weakSelf?.tableView.reloadData()
                weakSelf?.tableView.scrollToRow(at: IndexPath.init(row: self.items.count - 1, section: 0), at: .bottom, animated: false)
            }
        }
        
        DispatchQueue.main.async {
            if let state = weakSelf?.items.isEmpty, state == false {
                weakSelf?.tableView.reloadData()
                weakSelf?.tableView.scrollToRow(at: IndexPath.init(row: self.items.count - 1, section: 0), at: .bottom, animated: false)
            }
        }

    })
    
    Message.markMessagesRead(forUserID: self.currentUser!.id)
}