create UICollectionViewController subclass and add as a childviewcontroller - ios

Question

I am new to iOS development. I want to create collectionView in two different view controllers with same UI.I want to create only one UICollectionView and resuse it on different view controller instead of create separate collectionViews . On approach i can follow is to create the UICollectionViewController subclass and add this on my viewcontrollers as a childviewcontroller, but not sure if this is the correct approach do not know how addChildViewcontroller works and how to pass data between child and parent viewcontrollers. It would be great if someone can help on this. If any sample code is available to achive this please let me know.
Any help is much appreciated.

Answer 1

You can pass around the same collection view controller instance. Add it in viewWillAppear and remove in viewDidDisappear in first and second classes. Here is a sample code that you could use,
extension UIColor {
class func randomColor() -> UIColor {
let red = CGFloat(arc4random_uniform(255)) / 255.0
let green = CGFloat(arc4random_uniform(255)) / 255.0
let blue = CGFloat(arc4random_uniform(255)) / 255.0
return UIColor(red: red, green: green, blue: blue, alpha: 1.0)
}
}
class MyCollectionViewController: UICollectionViewController {
let data: [UIColor]
init(data: [UIColor]) {
self.data = data
let layout = UICollectionViewFlowLayout()
layout.itemSize = CGSizeMake(100, 100)
layout.scrollDirection = UICollectionViewScrollDirection.Vertical
super.init(collectionViewLayout: layout)
}
override func viewDidLoad() {
super.viewDidLoad()
collectionView?.registerClass(UICollectionViewCell.self, forCellWithReuseIdentifier: "cell")
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return data.count
}
override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier("cell", forIndexPath: indexPath)
cell.backgroundColor = data[indexPath.item]
return cell
}
}
class FirstViewController: UIViewController {
lazy var myData:[UIColor] = {
var allData = [UIColor]()
for i in 0 ..< 20 {
allData.append(UIColor.randomColor())
}
return allData
}()
var collectionViewController: MyCollectionViewController!
override func viewDidLoad() {
super.viewDidLoad()
collectionViewController = MyCollectionViewController(data: self.myData)
let barButton = UIBarButtonItem(title: "Show next", style: .Plain, target: self, action: "showNext:")
navigationItem.rightBarButtonItem = barButton
}
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
let collectionView = collectionViewController.view
collectionView.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(collectionView)
addChildViewController(collectionViewController)
collectionView.topAnchor.constraintEqualToAnchor(view.topAnchor).active = true
collectionView.bottomAnchor.constraintEqualToAnchor(view.bottomAnchor).active = true
collectionView.leftAnchor.constraintEqualToAnchor(view.leftAnchor).active = true
collectionView.rightAnchor.constraintEqualToAnchor(view.rightAnchor).active = true
collectionViewController.didMoveToParentViewController(self)
}
override func viewWillDisappear(animated: Bool) {
super.viewDidDisappear(animated)
collectionViewController.willMoveToParentViewController(nil)
collectionViewController.view.removeFromSuperview()
collectionViewController.removeFromParentViewController()
}
func showNext(sender: AnyObject) {
let secondViewController = SecondViewController(collectionViewController: collectionViewController)
navigationController?.pushViewController(secondViewController, animated: true)
}
}
class SecondViewController: UIViewController {
var collectionViewController: MyCollectionViewController!
init(collectionViewController: MyCollectionViewController) {
self.collectionViewController = collectionViewController
super.init(nibName: nil, bundle: nil)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
let collectionView = collectionViewController.view
view.addSubview(collectionView)
collectionView.translatesAutoresizingMaskIntoConstraints = false
addChildViewController(collectionViewController)
collectionView.topAnchor.constraintEqualToAnchor(view.topAnchor).active = true
collectionView.bottomAnchor.constraintEqualToAnchor(view.bottomAnchor).active = true
collectionView.leftAnchor.constraintEqualToAnchor(view.leftAnchor).active = true
collectionView.rightAnchor.constraintEqualToAnchor(view.rightAnchor).active = true
collectionViewController.didMoveToParentViewController(self)
}
override func viewWillDisappear(animated: Bool) {
super.viewDidDisappear(animated)
collectionViewController.willMoveToParentViewController(nil)
collectionViewController.view.removeFromSuperview()
collectionViewController.removeFromParentViewController()
}
}

Answer 2

I have a Set of Answers you can use,
My source Code is ParentViewController and ChildViewController are
same viewController to be declared.
First you create the ParentViewController and add the
UICollectionView then set the Cell size in ParentViewController.
Second you create UICollectionViewCell in same parentViewController,
then add what u need Label or Buttons to be declare.
In ParentViewController class declare 'UICollectionViewDelegate',
Ex: class MyViewController: UIViewController, UICollectionViewDelegate
Then Create UICollectionViewDelegate methods and i have put my
methods below,
func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return arrayvalue.count
}
func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier("reuseIdentifier", forIndexPath: indexPath)
// Configure the cell
let baseView = cell.viewWithTag(101)
let titleLabel = baseView?.viewWithTag(102) as! UILabel
titleLabel.text = arrayvalue[indexPath.row] as String
return cell
}
func collectionView(collectionView: UICollectionView,
layout collectionViewLayout: UICollectionViewLayout,
sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
return CGSizeMake(CellSize)
}
func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath)
{
collectionView.deselectItemAtIndexPath(indexPath, animated:true)
let storyBoard = UIStoryboard(name: "storyboardName", bundle: nil)
let name: classname = storyBoard.instantiateViewControllerWithIdentifier("reuseIdentifier") as! AnotherViewController
self.navigationController?.pushViewController(name, animated: true)
}
Very Important to give storyboard 'reuseIdentifier' value and also
give inside the class cellForItemAtIndexPath reuseIdentifier, example this line
let cell = collectionView.dequeueReusableCellWithReuseIdentifier("reuseIdentifier", forIndexPath: indexPath)
This code was working for me...