CollectionViewAdapter.swift

//
//  CollectionViewAdapter.swift
//
//  Created by Mohamed Hashem on 7/16/17.
//  Copyright © 2017 MAC. All rights reserved.
//

import UIKit

class CollectionViewAdapter: UICollectionView , UICollectionViewDelegate,UICollectionViewDataSource,UICollectionViewDelegateFlowLayout {
    
    var dataArray : Array<Any>!
    var cellSize : CGSize!
    
    private var reuseIdentifier = "Cell"
    
    var AutolayoutHeightConstraint:NSLayoutConstraint?
    
    var didSelectItemAt: ((_ index:IndexPath)->())?
    
    var CellConfigurator : ((UICollectionViewCell,_ index:IndexPath)->())?

    var emptyDataLabel:UILabel=UILabel()
    
    
    /// cell xib name should match theclass name
    func setup(cell:String,data:Array<Any>,cellsize:CGSize,AL_Height:NSLayoutConstraint?,cellConfig:((UICollectionViewCell,_ index:IndexPath)->())?)
    {
        dataArray = data
        cellSize = cellsize
        AutolayoutHeightConstraint = AL_Height
        CellConfigurator = cellConfig
        reuseIdentifier = cell;
        self.register(UINib(nibName: cell, bundle: nil), forCellWithReuseIdentifier: cell)
        
        self.delegate = self
        self.dataSource = self
    }
    
    /// emptyData---
    func SetEmptyDataLabel(label:String)
    {
        emptyDataLabel.textColor = #colorLiteral(red: 0.2549019754, green: 0.2745098174, blue: 0.3019607961, alpha: 1)
        emptyDataLabel.text = label
        addSubview(emptyDataLabel)
        emptyDataLabel.center = center
        emptyDataLabel.sizeToFit()
    }
    override func reloadData()
    {
        super.reloadData()
        emptyDataLabel.isHidden = dataArray.count != 0
    }
    override func layoutSubviews() {
        super.layoutSubviews()
        
        emptyDataLabel.center = CGPoint(x: center.x, y: height/2)
        
    }
    ///---
    
    
    // MARK: UICollectionViewDataSource
    
    func numberOfSections(in collectionView: UICollectionView) -> Int
    {
        // #warning Incomplete implementation, return the number of sections
        return 1
    }
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        // #warning Incomplete implementation, return the number of items
        return dataArray.count
    }
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell
    {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath)
        
        CellConfigurator?(cell,indexPath)
        // Configure the cell
        
        return cell
    }
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize
    {
        return cellSize
    }
    func AddItem(item:Any,Animated:Bool)
    {
        dataArray.append(item)
        self.reloadData()
        Stretch(Animated: Animated)
    }
    func removeItem(at index: IndexPath,Animated:Bool)
    {
        dataArray.remove(at: index.row)
        self.reloadData()
        Stretch(Animated: Animated)
    }
    func Stretch(Animated:Bool) {
        if let AutolayoutHeightConstraint = AutolayoutHeightConstraint
        {
            let topView = self.topMostController()?.view
            if Animated && topView != nil
            {
                UIView.animate(withDuration:0.5, animations:
                    {
                        AutolayoutHeightConstraint.constant = self.collectionViewLayout.collectionViewContentSize.height
                        topView?.layoutIfNeeded()
                })
            }
            else
            {
                AutolayoutHeightConstraint.constant = self.collectionViewLayout.collectionViewContentSize.height
            }
            
        }
    }
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        didSelectItemAt?(indexPath)
    }
    
  
    
    
}



// usage

class sampleCollectionCell: UICollectionViewCell {
    
    @IBOutlet weak var txtLabel:UILabel!
    
    override func awakeFromNib()
    {
        super.awakeFromNib()
    }
    
    func setup(data:String)
    {
        txtLabel.text = data
        
    }
    
    
}

class client: UIViewController
{
    @IBOutlet weak var collectionViewSample: CollectionViewAdapter!
    @IBOutlet weak var ConstCollectionHeight : NSLayoutConstraint!// constraint of the collection view Height / if you ont want animation ignore this line
    
    var dataArray : [String]? = ["hi","wow"] // if there is no initial data, you can ignore this line
    
    
    override func viewDidLoad()
    {
        super.viewDidLoad()
        
        // empty data label that show when there is no data
        collectionViewSample.SetEmptyDataLabel(label: "No data")
        
        // suting up the collectionViewAdapter
        let cellsize = CGSize(width:(collectionViewSample.width-10) / 2,height: 50)
        collectionViewSample.setup(cell: "sampleCollectionCell", data: dataArray ?? [], cellsize: cellsize, AL_Height: ConstCollectionHeight /* optional */ )
        { (cell, index) in
            (cell as! sampleCollectionCell).setup(data: self.collectionViewSample.dataArray[index.row] as! String)
        }
        
    }
    
    @IBAction func addItemClicked(_ sender: Any)
    {
        
        self.collectionViewSample.AddItem(item: "hello", Animated: true)
        
    }
    
    @IBAction func removeItemClicked(_ sender: Any)
    {
        self.collectionViewSample.removeItem(at: IndexPath(row: 1, section: 0), Animated: true)
        
    }
    
    
}