How to insert Item to a collectionView ? Swift3

Question

I am creating a chatting app in Xcode 8 with Swift 3 and I am using collectionView for the messages. but I am having an issue with inserting a new item to the collection view when press send:

msg.append(message) // msg : Messages Array    
let item = msg.count - 1 
let IndexPath = NSIndexPath(item: item, section: 0)
self.collectionView.insertItems(at: [IndexPath]) 

error show up ( Ambiguous reference to member 'collectionView(_:numberOfItemsInSection:)'

How to solve this issue. and is working with storyboard effecting the work with collectionView because I cannot change the cell size with :

 public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        if let messageText = msg[indexPath.item].text {
            let size = CGSize(width: 250 , height: 1000)
            let options = NSStringDrawingOptions.usesFontLeading.union(.usesLineFragmentOrigin)
            let esf = NSString(string: messageText).boundingRect(with: size, options: options, attributes: [NSFontAttributeName: UIFont.systemFont(ofSize: CGFloat(18))], context: nil)
            print("Changed")
            return CGSize(dictionaryRepresentation: esf as! CFDictionary)!
        }

          print("Not Changed")
        return CGSize(width: view.frame.width, height: CGFloat(100))

    }

I have but a break point and it has not been reached!

Answer 1

You are using UIViewController and not UICollectionViewController so you don't get the collectionView property for free. You need to drag in an outlet form your storyboard and name it @IBOutlet var collectionView: UICollectionView!.

Answer 2

in my case i reference self.tableView.SOMEMETHOD but there is no outlet exist with name "tableView". please review your code, i think it's issue of outlet